Chapter VII: Plato (427–347 B. C.) (1)

=Abdera and Athens.= The materialism of Democritus was the natural consummation of the thought of the Cosmological Period. The influence of the Sophistic psychology only enriched it, widened it, and brought its materialism into a systematic formulation. The Democritan system from the isolated centre of Abdera points only to the past. Upon the death of Democritus the school quickly disappeared. Its materialistic doctrine reappeared from time to time in one form and another,――in the Skeptics, the Epicureans, and the Stoics. It was reintroduced as a system into Europe during the Renaissance. So far as Greece was concerned, the school of Abdera was an early ripening and an early dying branch.

The school of Athenian immaterialism, the principal tendency of Greek thought, arose from the centre of Attic civilization and pointed to the future. It drew its materials from practically the same sources as the philosophy of Abdera, but the materials were polarized about the ethical teaching of Socrates. The life of Plato coincides with the unhappy history of Athens after the death of Pericles (429 B. C.). The Peloponnesian War began in 431 B. C., two years before the death of Pericles and four years before the birth of Plato; and it did not end until 403 B. C. The event most disastrous to the Athenians during this war was the Sicilian expedition in 413 B. C. Athens was captured by the Spartans in 403 B. C., and the great walls of the city were destroyed. The remainder of Plato’s life was contemporaneous with the devastating wars among the Greek cities, for there was no city strong enough to hold the balance of power after it left the hands of the Athenians. In 359 B. C. Macedon began to loom up as a power in the north. The life of Plato, the formulator of Athenian immaterialism, may be easily remembered as covering that period between the rise of Sparta and the rise of Macedon.

=The Difficulties in Understanding the Teaching of Plato.= The theory of Plato is one of the most involved and one of the most difficult to understand in the whole history of philosophy. This difficulty of interpreting Plato as a philosopher depends upon many factors: upon the artistic literary form of the dialogue in which his philosophy is presented; upon the conflicting tendencies of thought in Plato himself; upon the fact that the composition of his dialogues extended over a period of more than half a century; upon the constant reshaping of the content as well as the form of his thought; and upon the uncertainty of the chronological order of his writings. This chronological order of Plato’s dialogues is an important factor in determining his teaching. Since the beginning of the nineteenth century a vast amount of literature has been published on the subject, and many theories of the dialogue-chronology have been proposed. There are three principal groups of theories: (1) those based upon purely _a priori_ hypotheses, as, for example, that of Hermann, that each dialogue is a stage in the development of Plato’s thought; or that of Schleiermacher, that Plato had a systematic plan from the beginning; (2) those based upon an empirical study of the historical allusions in the dialogues themselves (Zeller, Windelband, _et als._); (3) those recent theories based upon the “stylometric test,” _i. e._ by an examination of the peculiarities of the style of Plato. Lutoslawski is a prominent representative of this method.

The result to the student is bewildering, on account of the differing conclusions. But since some choice must be made, we shall follow the order laid down by Windelband,[26] because it is fairly orthodox and conservative. For convenience to the memory, the writings will be grouped in the periods of Plato’s life. Our interpretation will therefore follow Windelband in respect to the character of Plato’s theory itself.

=The Life and Writings of Plato.= Two important events divide Plato’s long life of eighty years into three periods. These events were the death of his master, Socrates, in 399 B. C., and Plato’s return from Sicily in 387 B. C., after having there come under the influence of the Pythagoreans. His first period may be called his student life, and was twenty-eight years long; the second period was that of the traveler, and was twelve years long; the third period was that of teacher of the Academy, and was forty years long. The first half of his life therefore covers the first two periods, and the second half covers his period as teacher. Probably he was engaged in the composition of the dialogues during all these periods, and Cicero reports him to have died “pen in hand” (_scribens est mortuus_).

=1. Plato’s Student Life= (427–399 B. C.). This period closes with the death of Socrates. His acquaintance with Socrates began when he was twenty years old, and therefore lasted eight years.

The dialogues written during this period are presentations of the doctrine of Socrates and do not contain the constructive theory of Plato. They are concerned either with Socratic subjects or with Socrates personally, and were written in part during Socrates’ life, in part directly after his death.

(a) Dialogues written under the influence of Socrates:

_Lysis_, concerning friendship;
_Laches_, concerning courage;
_Charmides_, concerning moderation.

(b) Dialogues written in defense of Socrates:

_Crito_, concerning Socrates’ fidelity to law;
_Apology_, a general defense of Socrates;
_Euthryphro_, concerning Socrates’ true piety.

=2. Plato as Traveler= (399–387 B. C.). During this period Plato made one short and two long journeys, and after each he returned to Athens. Upon the death of Socrates he went to Megara, where a former pupil of Socrates had a school. Upon this journey he was accompanied by other pupils of Socrates, who, as tradition has it, feared violence to themselves after the death of their master. Plato remained in Megara but a short time, and soon returned to Athens. Immediately upon his return to Athens he went to Cyrene and Egypt, and was away from Athens about four years (until 395 B. C.). The Egyptian journey had little influence upon his thought, but must have stimulated his imagination. He then remained at Athens four years (395–391 B. C.), and during this time he taught a small circle and wrote his polemics against the Sophists.

In 391 B. C. Plato made his first Italian journey――to Sicily and southern Italy. This marks the second critical point in his mental development. For at this time (1) he came under the influence of the Italian Pythagoreans, and (2) he attempted and failed in connection with Dion[27] and Dionysius to erect his ideal state in Syracuse. He was sold as a slave by Dionysius, redeemed by a friend, and returned to Athens in 387 B. C., having been away about four years.

It is to be noted that Democritus and Plato were wide travelers, considering the difficulties of locomotion of the time. Both Democritus and Plato went to Egypt, and Democritus spent several years in Asia Minor (see p. 107).

The dialogues written during this period may be divided into (a) the group of polemics against the Sophists, and (b) the _Meno_.

(a) The polemics against the Sophists (written between his return from Egypt in 395 B. C. and his first Italian journey in 391 B. C.).

They are an attempt to present a solid front against the Sophists, and to show the weakness of the Sophistic doctrines. These polemical dialogues are:

_Protagoras_, a criticism of the Sophistic assumption that virtue
is teachable, because that assumption is incompatible with the
Sophistic fundamental principle;

_Gorgias_, showing how superficial the Sophistic rhetoric is when
compared with true culture, which is the foundation of real
statecraft;

_Euthydemus_, an exposition of the fallacies in the Sophistic
eristic;

_Cratylus_, a criticism of the philological attempts of the
Sophists;

_Theætetus_, a criticism of the Sophistic theories of knowledge;

The First Book of the _Republic_ (the “Dialogue concerning
Justice”), a criticism of the Sophistic naturalistic theory of
the state.

(b) _Meno_, which contains the first positive statement by Plato of his own constructive theory. It is the first intimation of development beyond the simple Socratic theory of knowledge. Plato states this, however, rather timidly, by suggestions and after the manner of a mathematician.

=3. Plato as Teacher of the Academy= (387–347 B. C.). These forty years were spent by Plato in Athens as master and teacher of his school, the Academy, with the exception of two journeys to Italy. He undertook these journeys in the hope of realizing in a practical way his political ideals. He made his second Italian journey upon the invitation of Dion, in the hope of influencing the younger Dionysius, and the third Italian journey in order to reconcile Dion and Dionysius. This last journey brought him again into great personal danger.

What was the Academy? It was a public grove or garden in the suburbs of Athens (see map, p. 219) that had been left to the city for gymnastics by a public-spirited man named Academus. It had been surrounded by a wall and had been adorned by olive trees, statues, and temples. Near this inclosure Plato possessed by inheritance a small estate. It was here that he opened his school, and few places could be more favorable for the study of philosophy. Plato bequeathed this estate to the school, which held the property in a corporate capacity for several centuries. The leader of the school was called scholarch, and he appointed his own successor. The school was a kind of religious brotherhood based upon the worship of the Muses.

Note that Democritus, Plato, and Aristotle finished their education at an age much beyond what is supposed to be the limit in modern time. They were, in fact, mature men before they began their life work. Plato was 32 before he began to teach in Athens and 40 before he set himself about his real life task in the founding of the Academy. Democritus was 40 before he returned to Abdera from his travels in Asia Minor. Aristotle was 41 when he undertook to act as tutor of Alexander, and 49 when he began his administration of the Lyceum.

The dialogues of the third period of Plato’s life contain his constructive theory, and are his masterpieces of art. The topics with which they deal show the advance of his thought over the dialogues of his first period. The purely Socratic dialogues were ethical discussions; these are ethical, metaphysical, and physical.

_Phædrus_, Plato’s delivery of his programme upon his entrance
into active teaching in the Academy, in 386 B. C.

_Symposium_, an exposition of his entire doctrine in “love
speeches.” It is the most artistic of his writings, and
represents the climax of his intellectual power (385 or
384 B. C.).

_Republic_ (major portion). The composition of the _Republic_
extended over a long period. It is a discussion: (1) concerning
justice (written in the second period, see above); (2) concerning
the ideal state which shall realize justice; (3) concerning the
Idea of the Good and in criticism of the constitutions of states.
It is Plato’s masterpiece and his life work.

_Parmenides_ and _Sophist_, written to express the objections to
the theory of Ideas, and to discuss such objections. (Windelband
holds these dialogues were not written by Plato, but by some
member of his school. This is, however, not the consensus of
opinion.)

_Politicus_, a discussion of the field of knowledge and of action
for a statesman.

_Phædo_, Plato’s final will and testament to the school, written
shortly before his third Sicilian journey, in 361 B. C. It is
his completed conception of the Idea of the Good and of the
relation of other Ideas to it. It contains Anaxagorean and
Pythagorean elements.

_Philebus_, concerning the ingredients of the Idea of the Good.

_Timæus_, Plato’s conception of physical nature, expressed in
mythical form.

_Laws_, the work of Plato’s old age, his revision of the ideal
State.

=Concerning the Dialogues[28] of Plato.= The early philosophers presented their philosophy in metrical form as poems “concerning nature”; Socrates perpetuated his teachings through conversations with men; Plato made his influence permanent by written dialogues; Aristotle’s philosophy, in the works that have been preserved, stands in the form of treatises whose sole purpose is that of exposition. Plato’s dialogues therefore have a twofold place in the history of literature. On the one hand, in the history of literature proper we have already mentioned them as standing after the Greek drama in the development of Greek dialectics; on the other hand, in the development of philosophical instruction they stand between the conversations of Socrates and the scientific expositions of Aristotle.

Plato was the first child of Fortune, and the complete preservation of his works was the most remarkable proof of it. Æschylus was the author of at least 70 writings, of which 7 are preserved; Euripides was the author of 95 writings, of which 18 are preserved; Sophocles had 123 writings, aside from his lyric works, of which 7 are preserved. Shakespeare wrote 36 plays, Plato wrote 35 dialogues that are genuine. All of Plato’s writings have come down to us. Why were the writings of Plato preserved from the destroying hand of time? There are at least three causes of their preservation: (1) they had intrinsic beauty; (2) there was contemporary public interest in them; (3) the chief cause, Plato’s school kept close guard over them.

By the dialogue Plato could employ the Socratic method, give dramatic effect, and idealize Socrates. The _Republic_ is his crowning literary effort, and the most complete statement of his mature political views. Perhaps the _Philebus_ is the best expression of his idea of goodness, and presents his most complete organization of the sciences. All Plato’s dialogues have a transparent beauty and a purity of diction; and they may be taken as a revelation of himself. All are dialogues save the _Apology_, but the dialogue element grows less and less in his later works. Socrates is usually the spokesman in them, and to him is usually given the deciding word. Only a few have a fixed plan of argument. One thread and then another is followed, and in many no decision whatever is reached; for the dialogues must always be taken as artistic products in which philosophical experiences are idealized. Plato often employs myths or parables to illuminate his arguments. The situations and the literary adornments show the human touch, and the conversation often moves to a dramatic close.

In the _Republic_ Plato sought to formulate theoretically certain political conceptions of the ideal State that were then in the air. It is interesting to note that his conception influenced the political idealism of later time, as, for example, Cicero’s _De Republica_, Augustine’s _City of God_, More’s _Utopia_, Campanella’s _State of the Sun_, Bacon’s _New Atlantis_, Macchiavelli’s _Il Principe_.

=The Factors in the Construction of Plato’s Doctrine.=

=1. His Inherited Tendencies.= (a) In the first place Plato was by instinct an aristocrat. His family was one of the most distinguished in Athens, and traced its descent from Solon and Codrus. In making an estimate of his philosophy one must take account of the caste of society in which he was born. His metaphysical theory of Ideas is aristocratic, and in it he turns from all that is of the earth earthy to what is above the life of “opinion.” His four cardinal virtues are possible only to the few. His political attitude was peculiar. He was hostile to the democracy, and yet his political idealism diverged so far from the practical politics of Athenian aristocracy that he completely abstained from public life. With Plato, philosophy once more retires to the school. Here we have the strange juxtaposition of Socrates, the teacher, who had been engaged in a practical reformation, whose father was an artisan and whose mother a midwife, and Plato, his adoring pupil and truest interpreter,――Plato, the idealist, “whose speculation is not like the Philistine, whose life is spent in the market place or the workshop, and whose world is measured by the narrow boundaries of his native town; it is the lord of the manor, who retires to his mansion, after having seen the world, and turns his gaze towards the distant horizon; disdaining the noise of the cross-roads, he mingles only in the best society, where is heard the most elegant, the noblest, and the loftiest language that has ever been spoken in the home of the Muses.”[29]

(b) In the next place Plato had an instinctive love for the beautiful, and in this he was great, even in his time. Every Periclean Greek was artistic, but Plato was more than this. He is to be ranked among the great creators of the art of his day,――with Phidias and Sophocles. He represented in his person everything ideally Greek. He was a man of great beauty, a human Apollo, a man endowed with every physical and mental talent, and his moral character was almost ideal in its purposes. His real name was Aristocles, and he got his name Plato from his broad frame. The artistic development of the time appealed to him in his youth, and he was early interested in the writing of epic and dramatic poetry. This artistic instinct determined in no small measure not only the form of the presentation of his thought, but also the content of the thought itself. It determined his principle of conceiving the Ideas, the constitution of his State, his theory of pleasure, and his conception of the highest Good. The artistic form of the presentation of his writings was as important to him as the matter presented.

=2. His Philosophical Sources.= Plato had received a careful education that made him familiar with all the scientific theories of current interest to the Athenians. The elements of the earlier philosophies, that were fundamental to the mechanical atomism of Democritus, were recombined in a different way by Plato under the influence of Socrates’ ethical principle. Even Plato’s political and artistic ideals are subordinate to his entire absorption in the personality and teaching of Socrates. Heracleitus, Protagoras, Parmenides, and, later, Anaxagoras and the Pythagoreans, furnished him with his philosophical materials. We may point out three of the preceding philosophies that had an especially powerful influence upon him: those of (1) Socrates; (2) Parmenides; and (3) the Pythagoreans. His revered master, Socrates, furnished Plato throughout with the conceptual principle, by which he worked over all his material into his daring system. The influence of Parmenides upon him was also very great. He speaks of the Eleatic as “Parmenides, my father.” Plato betook himself to the Eleatic school at Megara upon the death of Socrates, and this shows that he must already have been hospitable to the philosophy which taught the conception of an absolute and eternal essence of things known by the human reason. The influence of the Pythagoreans was felt by Plato on his first visit to Italy. This influence grew with him, and seems to dominate the dialogue of his old age, the _Laws_. The Eleatic Oneness was a single, immutable block. In the Pythagorean doctrine of numbers he found the conceptual divisions of that Oneness, and he also found that such conceptions would give a content to Socrates’ conception of the Good. Indeed, the numbers seemed to be the conceptual models for which Socrates was searching. Mathematical truths are independent of perception. They are innate ideas. They are eternal and immutable Forms. They were the weapons needed against the Protagorean doctrine of perception. While Plato agreed with Heracleitus that the visible world is a changing world, and with Protagoras that our sense-perceptions of that world can yield only relative truth, he developed his philosophy almost entirely on its conceptual side; and this is due to the influence first of Socrates, second of Parmenides, and third of the Pythagoreans. Plato’s completed philosophy was the theory of Ideas, worked over in his mind a half-century or more, and is in itself a history of the development of pure concepts.

=The Divisions of Plato’s Philosophy.= Plato himself had no clear conception of an exact division of science, and did not confine himself in a single dialogue to a single science. Aristotle, however, distinguished in the philosophy of his master dialectic, ethics, and physics, and these divisions of Plato’s teaching have been traditionally adopted. The dialectic, as commonly used in his time, meant “the dialogue or conversation employed as a means of scientific investigation.” It was transformed by Plato to mean not logical but metaphysical discussion. Plato was concerned with the laws of Being rather than the laws of logic, and, as Being to him consisted of Ideas, his dialectic interest was to reduce experience by division and induction to some unity. Plato’s dialectic was not logical but methodological,――logical operations taken as a whole,――by means of which the Ideas and their relations to one another were to be found. The physics of Plato is of little value. It was an afterthought to satisfy the demands of his school. The world of nature phenomena could never be for Plato the object of true knowledge. Unfortunately, the teleological physics of Plato was regarded by the Hellenistic time and the Middle Ages as Plato’s most important achievement. Plato wrote entirely in the spirit of the Enlightenment, and his works show a great interest in man as a moral being, but little interest in physical nature.

=Summary of Plato’s Doctrine.= The interpretation of Plato as set forth in what follows may be thus summarized: Plato began with the conceptual form of idealism, suggested by the logical method of Socrates, with the purpose of solving logical and ethical problems. He advanced to a teleological idealism, conditioned by the doctrines of Anaxagoras and the Pythagoreans, with the purpose of applying his doctrine to physical problems.

=The Formation of Plato’s Metaphysics.= In his earliest period Plato made these very clear statements: (1) virtue is knowledge; (2) by knowledge is not meant sense-perceptions. In his final statement of his philosophy, as he bequeathed it to posterity, he only gave a new evaluation of these two early principles, although he expressed them in a highly complex form. “Virtue is knowledge” is the basis of agreement between Socrates and the Sophists; and “by knowledge is not meant sense-perceptions” is the basis of their opposition. During Plato’s early period he was acting as a faithful transcriber of Socrates in the presentation of this first principle: virtue is knowledge, is teachable, is one. During Plato’s second period he was called on to defend the second statement against the Sophists. Plato’s formation of his own theory begins at this point,――at the point where his defense of his master was keenest. From this time, for a full half-century, Plato developed the Socratic principles in a theory that went far beyond Socrates, but that was never untrue to him.

The simplest way of stating Plato’s formation of his own doctrine is this: he accepted the Protagorean doctrine of a perceptual world of relative knowledge; he placed it beside the Socratic theory of conceptual reality; and as a result he conceived the world to be twofold. Both Being and Becoming share in reality. There are, on the one side, the immutable concepts that compose true reality; there are, on the other side, the changing perceptions that come and go. The world of true reality _is_, but never _becomes_; the world of relative reality _becomes_, but never _is_. These two worlds are by nature separate; one is the object of the reason, the other is the object of the senses; one is incorporeal, the other is corporeal. The first world is the immutable One of the Eleatics presented by Plato as a plural number of Socratic concepts; the other world is the Heracleitan flux presented as perceivable things. There is true knowledge, but Protagoras is right in saying that it cannot be found in the perception of the material world. It is knowledge of an incorporeal world, and that is precisely the world of Socratic concepts which now in Plato’s hands become Ideas.

It would, however, be a mistake to suppose that Plato’s conception of the world was an artificial eclecticism, obtained by putting two worlds side by side. To be sure, he never was able to bring them into an organic unity, and the dualism between them is often very marked. But they do not lie like two drawers in a desk, each having no vital influence on the character of the other. In the juxtaposition of the two worlds each gets a new meaning, and the value of each becomes greater.

In the first place, _perception[30] gets a new value_. The logic of the Sophistic doctrine of perception was that perceptions are the only form of knowledge, and even perceptions have no share of truthfulness. Protagoras himself did not go so far as this absolute skepticism, but this is the logic of his position. Perceptions can have no value, because each is a standard to itself. Plato incorporates the perception theory into his own, and immediately gives it a new value. Perceptions do not, to be sure, yield true knowledge, but they have a relative value. They have a value for the practical world, although the highest they can give is Right Opinion. When we remember that the world of that day was weary of its own speculations leading to nihilism, it is remarkable that Plato did not turn away entirely from the doctrine of the Sophists. On the contrary, he took up the Sophistic doctrine into his own and gave to it a value which it had not possessed by itself.

In the second place, _conception gets a new value_. What was conception to Socrates? It was the common content of opinions and perceptions; it was the universal that was developed inductively out of many particulars. Socrates brought many particulars together in order to reveal their common qualities. The abode of conceptions was to Socrates the half-formed individual opinions and experiences in which conception lay, as in an envelope; and the conversation was needed to bring it forth. The concept to Socrates was the logical “nature” of perceptions. But now since Plato admitted the relative reality of all perceptions, he was obliged to look elsewhere to account for conceptions. If the conceptions are true reality, they cannot be the common quality in opinions, nor the logical “nature” of changing perceptions. The true conception cannot be contained in the perception. Accordingly the conception must exist in an incorporeal world and possess an independent reality. The concepts are hypostasized by Plato. They become Ideas. Thus the Socratic concept became the Platonic Idea, and _for the first time in European thought, reality is conceived as immaterial_. The conceptual world grows under Plato’s hands to be “other than” the perceptual world, and this was his first step beyond Socrates. The conceptual world is the perfect reality that cannot be contained in any material thing nor in the sum of all material things. The immaterial Ideas are the object of thought, as nature phenomena are the objects of perception. Ideas are not the abstractions of perceptions, for the process of thought is not an analysis nor an abstraction, but an intuition of reality presented in single instances. Ideas are the reality of which perceptions are the copies or shadows. Perceptions do not contain the truth. They are only the suggestions or promptings by which the soul bethinks itself of the Ideas. Material things merely hint to the soul of the existence of the Ideas.

It is important in this connection to point out that Plato’s conception of immateriality is not to be taken as what we mean in modern times by the spiritual or psychical; for, according to Plato, our psychical functions belong to the world of Becoming, just as the functions of our body and other perceptual things belong to it. Besides, even the Ideas of sense qualities have reality. Plato does not identify the human mind with the incorporeal world of Ideas, nor does he make the modern dualistic division of the world into mind and matter. The immaterial world is “other than” the world of perception, and bears the relation to the material world of the unchanging to the changing, of the simple to the manifold, of Being to Becoming.

=The Development of Plato’s Metaphysics――The Development of Plato’s Ideas in the Two Drafts.= The twofold world with its new evaluation of the Socratic conception and of the Protagorean perception was, after all, only Plato’s point of departure for his constructive work. It was his first and undeveloped apprehension of a theory of Ideas. It appeared first in the _Meno_ in his doctrine of recollection and immortality, which was written in his second period just after his series of splendid polemics against the Sophists. From this time for a full half-century Plato developed the conception of a twofold world into a Theory of Ideas. In the course of time he found himself confronted with three problems: (1) How many Ideas are there? (2) What is the relation between Ideas and physical things? (3) What is the relation of the Ideas to one another? Plato’s answers to these three questions compose what is known as his Theory of Ideas. However, he answers these three questions differently when he first considered them than later, when his grasp upon the significance of his problem became more mature. Plato’s Theory of Ideas, therefore, may be said to have had a development in two stages. These two stages are called his “two drafts” (Windelband) of the Ideas. We shall now present, first in summary form and then in more detail, his answers to these three questions in the two drafts, and thereby show how his theory developed to its final formulation.

=Brief Comparison of the Two Drafts of the Ideas.=

=1. The Earlier Draft of Ideas.=

(a) _The Number of Ideas_ is infinite.

(b) _The Relation of Ideas to Physical Things_ is similarity. The Ideas on their side are spoken of as having a “presence” in physical things, but never fully appearing in them; the physical phenomena on their side are spoken of as “participating” in the Ideas.

(c) _The Ideas are Related to One Another_ logically, as genera to species, but they are only roughly classified by Plato.

=2. The Later Draft of Ideas――Plato’s Final Statement.=

(a) _The Number of Ideas_ is limited to those of worth, mathematical relations, and nature-products, but Plato never arrived at any definite selection.

(b) _The Relation of Ideas to Physical Things_ is teleological. The Ideas are the ideal or purposeful ends of physical objects.

(c) _The Ideas are Related to One Another_ teleologically. The Idea of the Good stands at the head, and is the purposeful end of all the other Ideas.

=Comparison of the Two Drafts of Ideas in More Detail.=

=1. The Number of Ideas in the Earlier and Later Drafts compared.= When Plato first presented the Theory of Ideas to himself, he conceived their number to be infinite. There are Ideas of everything that is thinkable. There are as many as there are class concepts, as there are qualities of things in the universe, as there are common nouns in the language. But it was pointed out to Plato that he had only reproduced and paralleled in the immaterial world what exists in the material world; that such a theory did not solve, but only doubled our difficulties. Then there were technical difficulties in the conception of the Ideas of everything――of things, qualities, relations,――good, bad, and indifferent. But what probably appealed to him most cogently was the raillery to which he found his theory subjected (see _Parmenides_), that he as a Greek could think of ugly Ideas, like hair and filth, as real. The result was that in the later drafting of his theory the number of qualities worthy to be called Ideas becomes very much limited. Plato makes the elimination from no avowed principle except that of worth, because as a Greek it was absolutely repellent to him to regard anything as real except worth. Consequently in his later dialogues he speaks of (1) Ideas having an inherent value, like the Good and the Beautiful, (2) Ideas corresponding to nature products, (3) Ideas of mathematical relations. Norms of value thus take the place of class-concepts, and in his selection of Ideas his choice is determined more and more by their moral worth.

=2. The Relation of Ideas and the World of Nature in the Two Drafts compared.= Plato did not construct his world of Ideas in order to explain the world of physical nature. His original purpose was to find an object for knowledge; and his Ideas were born out of his striving to give a reality to the conceptions of Socrates. In his evaluation of the doctrine of his master he had drawn a distinction between the two worlds, but he had not thought of explaining one by the other. They were related and distinguished, but one threw no light upon the other. In Plato’s first draft of the Ideas he speaks of this relation as _imitation_. The phenomena are an imitation of reality. The Ideas are the originals and physical objects are copies. To state the relation in modern terms, the laws of the growth of a tree are permanent, while the tree changes. The lower world of Becoming has a similarity to the higher world of Being. As the Pythagoreans had conceived things as imitations of numbers, Plato, strongly influenced by the Pythagoreans, thought that concrete things correspond to their class concepts only in a degree. On the one hand, the individual thing partakes of the universal of the Idea, and this is called “participation” in the Idea. On the other hand, the word “presence” describes the way the Idea exists in the thing, which means that the Idea is present in the thing so long as the thing possesses the quality of the Idea. The Ideas are present and then withdraw, and thus the perception changes.

In the second drafting of the Ideas, Plato has become conscious of the need of explaining physical nature by the Ideas. He did not at first think of explaining the nature of the physical world by his metaphysical reality. It was an afterthought, and arose out of the compulsion of having a systematic theory. His conception of the world of Ideas as the world of true Being ultimately demanded that the world of physical nature should be not merely “other than” but dependent upon the Ideas. The Ideas are unchanging; the phenomena are changing. If the Ideas are the reality of the changing world, in what other sense can they be its reality than as its cause? The _Meno_, _Theætetus_, _Symposium_, and _Phædrus_ do not discuss this problem. The _Sophist_ proposes it, and in the _Phædo_ the thought is first expressed that the Ideas are the causes of physical phenomena appearing as they do appear. But how can the Ideas be causes, when the very conception of them as pure and immaterial realities denies to them all qualities of motion and change? The Platonic theory reached its zenith in its solution of this problem. The Ideas must be conceived as the causes of nature phenomena, and still as not moving nor suffering change. They are teleological causes. They are the realized ends of the phenomenal world. The world of Ideas is the actual goal of perfection for _physical_ nature. The world of Ideas is not only the truth of all knowledge; it is also the perfect teleological cause of all actual change. This thought is developed in the _Philebus_ and the _Republic_, where the Ideas as a whole, and in particular the Idea of the Good,――to which all the other Ideas are means,――stand as the final cause of all occurrence. The physical phenomena stand therefore in a teleological relation to the Idea of the Good. From the Good all things get their meaning. It permeates and explains all.

=3. The Relation among the Ideas in the Two Drafts compared.= It was natural that the conception of a pluralism of Ideas should lead Plato to a consideration of the law of their relationship. A systematic theory of a multiplicity of reals involves their orderly relationship. They cannot exist independently in the same world. What is the relationship among the Ideas? In the earlier drafting of his theory Plato was principally attentive to the relations of coördination and subordination among the Ideas; in the possibility of the division of class concepts into genera and species. The relationship that he sought was logical relationship, the relationship that the scientist seeks to find in the classification of plants or rocks. Just what result Plato tried to reach by such a logical classification of his realities, it is difficult to say. He was not successful. His attempt to erect a logically arranged pyramid of conceptions with the most abstract at the apex was not carried out.

In his second drafting of the Ideas, Plato felt the inadequacy of a mere logical relationship among them, and conceived them to be teleologically related. His reduction of the number of Ideas had naturally brought about a new conception of their relationship. There must be some principle for their elimination, for the rejecting of some and the keeping of others. That principle was the principle of their ethical worth. That is to say, the Idea of the Good, which had been the standard for eliminating some concepts from the list of Ideas and for retaining others, now became for him the principle of the relationship of the Ideas among themselves. Plato turned from the logical to the teleological relation among Ideas. The Idea of the Good embraces and realizes all the others. It is therefore the absolute end of all the other Ideas, and they bear the relation to it, not of particulars to a general term, but of means to an end. The principle in their selection becomes the principle of their arrangement.

=Plato’s Conception of God.= The above sketch of the formation and development of Plato’s theory of Ideas shows how difficult it would be to frame a short definition of them that would at the same time be adequate. As he finally defined them, they are immaterial archetypes or ideals, dominated by a moral purpose. This dominating moral purpose in the Ideas is the highest Idea of all, the Idea of the Good, which stands above all the others and gives to them and to everything else their value and indeed their actuality.

Is this Idea of the Good the same as God? Plato calls the Good “Deity” and the “World Reason,” and ascribes to it the name of Nous. Nevertheless the Idea of the Good is not the same as the Christian God, and Plato is only showing here the influence of Anaxagoras’ conception upon him. (See p. 47.) The Idea of the Good is not a person or a spiritual being. It is merely the absolute ethical end and purpose of the world. Plato did not attempt to give it a content, any more than did his master, Socrates; but Plato presupposed it, because it was in itself the simplest and most comprehensible thing in the world.

=Plato’s Conception of Physical Nature.= Plato constructed a rough sketch of the philosophy of nature in his later years, in compliance with the needs of his School, and perhaps with the urging of his pupil, Aristotle. In his earlier period, he would have nothing of physics, and was in this respect quite in accord with the spirit of Socrates. To the end of his life he maintained that there can be no true knowledge of the physical world; for it is a world of change, and therefore all scientific conclusions about it could be only probable. In a mythical account in the _Timæus_ he drew a picture of the constitution of the world. He conceived a Demiurge or world-forming God to exist, and he thought that this God made the world out of not-Being or empty space “with regard to the Ideas.” The world thus constructed is conceived by Plato as a huge living thing, composed of a visible body and an invisible soul. The world-soul sets the world-body in a circular motion, which motion was considered by antiquity to be the most perfect of all motions. In sharp opposition to the mechanical theory of the world, Plato conceived the world to be endowed with knowledge, of which the spherical motion in its return upon itself is the symbol. The world is unitary and unique, the most perfect and most beautiful world, and its origin can be traced only to a reason working toward ends. Plato’s physics, of which the above is an abbreviated account, will be seen to be of little importance; but it was unfortunately, as we have said, this side of his doctrine that was emphasized in the Middle Ages.

This mythical account shows, however, the inherent dualism in Plato’s doctrine. The Idea never fully realizes itself in corporeal things, and Plato was called on to explain the cause of the evil and imperfection of the physical world. Moreover, the imperfection of the physical world got new emphasis in the influence upon him of the Pythagorean doctrine, which had set the perfect and imperfect worlds in opposition. What prevents the Idea from fully appearing in phenomena? The more Plato conceived the world of Ideas as ethical Ideals and a kingdom of pure worth, and the more teleological the Ideas became, the less could he regard the Ideas as the cause of imperfection in nature. Ideas are Being, and the essence of perfection. The cause of imperfection must therefore be that which has no being whatsoever. The physical world as “becoming” has participation, not only in that which has Being (Ideas), but in that which has no Being (empty space). The physical world has a composite character. It has sprung from the union of the Ideas and an absolutely negative factor, which Plato calls empty space. This eternal negative is formless and unfashioned, but it is capable of taking on all possible forms. The physical universe is therefore neither Ideas simply, nor matter simply, but a composition of the two. This non-Being is not like the matter, “unformed stuff,” of Aristotle, from which all sensible things are made; but it is that in which Ideas have to appear. The Ideas are plunged into this empty non-Being, which they take on as a veil. And just this is the origin of imperfection; non-Being withholds the Ideas from perfect expression. Non-Being, or empty space, is an indispensable auxiliary to the Ideas, for without it no physical universe would be possible. But at the same time it is the eternal foe and obstruction of the Ideas. Its coöperation with the Ideas is at the same time a resistance to them. It is the perpetual negation of Being, and the primary cause of imperfection, change, and instability. On this account the universe can never be like the Ideas, but it can approximate them. The soul of the world, for example,――which was regarded by Plato in Pythagorean fashion as number subjecting chaotic space to harmony,――is the most perfect reproduction of the Idea of the Good. The existence of matter detracts from the perfection of the world, but it does not detract from the majesty of the Ideas.

=Plato’s Conception of Man.= Plato needed a psychology of another sort from that developed by the Cosmologists. His analysis of the mental life of man stands or falls with his metaphysical theory of Ideas, but it has this importance: it is the first attempt to understand the psychical life from within.

The dualism of the two worlds appears in sharp outlines in the narrower field of the life of man. The soul of man belongs to both worlds. On the one hand, it belongs to the world of Becoming and partakes of that world through its sense-perceptions, desires, and their pleasures. In this lower world it is the principle of life and motion; it is that which moves itself and other things. On the other hand, it shares in the world of Being through its intuitive reason or knowledge. It shares in the instability and change of psychical phenomena; it also possesses the immutability of reality. Through its perceptions it constructs its “opinions” or inferences of changing phenomena; through its reason it has true knowledge of the eternal Ideas. Therefore the soul must bear in itself traits that correspond to the two worlds. Plato conceives man to have an irrational and a rational nature; and he divides the irrational nature into two parts,――the noble irrational part and the ignoble irrational part. The rational part of man is the reason, the noble irrational part is the will, the ignoble irrational part is the sensuous appetites.

{ Rational nature ＝ reason
Man { Irrational nature { Noble ＝ will
{ { Ignoble ＝ sensuous appetites

This is the celebrated doctrine of the “three parts” of the soul. Are they three parts or three functions of the soul? Plato is not clear as to this point. He sometimes speaks of them as three divisions, and treats them as separable in such a way that only the reason is immortal and the other two parts are mortal. Again, he speaks of the soul as a unity, which carries with it in the next life all three functions. In this latter meaning the three parts are three natures or three different degrees of worth of the unitary soul.

=Plato’s Doctrine of Immortality.= Beginning with this conception of the dual nature of the human soul, Plato reasons both backward and forward from it: backward to its pre-existence, and forward from its post-existence,――its existence after death. In the _Phædo_, Plato has put into the mouth of what has become his Platonized Socrates his final thought concerning the relation of this present life to its past and its future. It is plainly the doctrine of the transmigration of souls, which he got from the Pythagoreans. The soul has a reality that is imperishable, and the soul is rewarded or punished for its conduct in one existence by the kind of existence into which it is metamorphosed. In prison, on that fatal day when he drank the poison, Socrates explained to those around him why he was so cheerful at the thought of death. Is not our present existence a kind of death? Is not the soul in the present life deterred from true knowledge by the trammels of the bodily desires? The true philosopher is he who turns away from his body’s passions,――dies to them, and tries to live the reality of the world of Ideas. We shall have full knowledge when we pass beyond the grave and then we shall be rewarded, if we have striven truly. But at present our body hampers and misleads us with its perceptions of changing mortality around us, and with its transitory desires. This life itself is the reward or punishment for our conduct in our preceding state.

=1. The Immortality of Pre-existence.= What proof does Plato offer for our existence before this life? The Ideas, these testimonies of reality, form a part of the human soul. They are eternal, and have not been created by the soul. Knowledge is not the origination of a new truth, but is the recognition of Ideas, whose presence the mind merely records. Greek psychology never got much farther than this. The modern psychological conception of the soul as a dynamic something, which creates its own content, was quite foreign to the Greeks. To Plato, as to all other Greeks, the soul is as passive as the wax that receives the impress of the seal. All Greek psychology was under this general limitation: all ideas must be “given” to the soul. Therefore if the Ideas are not “given” by perception, because perception is of the changing; if nevertheless the soul finds itself in possession of the Ideas on the occasion of perception; if the soul did not create the Ideas, because the soul is by nature passive; the logical and only conclusion is that the soul was already in possession of the Ideas in a pre-existent state. Pre-existence is the only way of accounting for the full-born knowledge of the soul, and it is interesting to note how important was the pre-existent state to the imagination of the ancient world.

Plato therefore advanced the doctrine of reminiscence, or as he called it, _Anamnesis_, as proof of our pre-existence. Knowledge is recollection. The Ideas have always been present in the mind, and when we recognize them we have knowledge. The Ideas have no past or future, but they always exist. It is the mind that undergoes awakening――an awakening to their existence in itself. When the mind sees the objects of physical nature, it awakens in painful astonishment at the contrast between the sense world and the Ideas of its native world of immateriality. In a mythical representation in the _Phædrus_, Plato supposes that before the present life our souls have beheld the pure Ideas in their full reality, that the Ideas had been forgotten in our birth into the present life, but that the perception of similar corporeal things calls the soul back to the Ideas themselves. Then the “Eros” is awakened――the native philosophical impulse or inborn love for the Ideas, by which the soul is raised again to the knowledge of that true reality. Only the pure Ideas themselves will satisfy this longing; the embodiment of the Ideas in art or personalities is not adequate. The Eros ties us to the Ideas. God does not have this longing, for He fully knows the Good. The ignorant man does not have this longing, for he does not suspect the existence of the Ideas in himself. The Eros is the homesickness that the lover of the truth feels.

Our birth is but a sleep and a forgetting,
The soul that rises in us, our life’s star,
Hath had elsewhere its setting,
And cometh from afar;
Not in entire forgetfulness,
And not in utter nakedness,
But trailing clouds of glory do we come
From God, who is our home.[31]

When, in the _Meno_, the Sophistic dilemma was proposed to Socrates, “How can inquiry be made into what we know or into what we don’t know?” Socrates pointed out that the only escape from the dilemma was the process of recollecting, and that knowledge is the thing recalled. Socrates then called a slave to him, and by skillfully questioning him found that the slave recognized the mathematical relationship between the square on the hypothenuse of a right triangle and the sums of the squares on the other two sides. “The ignorant slave can only have been recollecting,” says Socrates. Mathematical knowledge is extracted from the sense-perception of the slave only because the slave has through such perception the opportunity of recollecting Ideas present in himself and not hitherto suspected by himself. In Plato’s system, mathematical forms have an important place. They are the links by means of which the Idea shapes space teleologically into the sense world.

=2. The Immortality of Post-Existence.= Plato’s ground for belief in the existence of soul after death is practically the same as that for its previous existence. Its destiny hereafter depends upon how far it has freed itself in this earthly life from the sensuous appetite. As proofs for future existence Plato mentions the soul’s possession of the Ideas, the simplicity and unity of the soul, the soul as the principle of life, and the goodness of God. However weak Plato’s arguments may be for the existence of future immortality, his absolute belief in it is one of the chief points in his teaching. It is interesting to note that the modern western world seems to have no concern in the previous state of the soul, but through the influence of the Christian religion has focused its attention upon the future life. Oriental religions contain the doctrine of pre-existence and the transmigration of souls, but not in the same sense as Plato. In Plato the soul possesses an identity that persists. It has all the qualities of the Ideas, but is also an entity possessing these qualities. It has non-origination, indestructibility, unity, and changelessness. The doctrine of the immortality of post-existence had appeared in the Greek religion, but this is the first time that we have found it as a part of philosophic teaching. The student will, of course, feel the difficulties in Plato’s conception as he has presented it. For how can the soul preserve its individuality as a unity, when the soul belongs in part to a world which is temporal?