Plato was born at Ægina (in which island his father enjoyed an estate as clêrouch or out-settled citizen) in the month Thargelion (May), of the year B.C. 427. His family, belonging to the Dême Collytus, was both ancient and noble, in the sense attached to that word at Athens. He was son of Ariston (or, according to some admirers, of the God Apollo) and Perictionê; his maternal ancestors had been intimate friends or relatives of the law-giver Solon, while his father belonged to a gens tracing its descent from Codrus, and even from the God Poseidon. He was also nearly related to Charmides and to Critias—this last the well-known and violent leader among the oligarchy called the Thirty Tyrants. Plato was first called Aristoclês, after his grandfather, but received when he grew up the name of Plato, on account of the breadth (we are told) either of his forehead or of his shoulders. Endowed with a robust physical frame, and exercised in gymnastics, not merely in one of the palæstræ of Athens (which he describes graphically in the Charmides), but also under an Argeian trainer, he attained such force and skill as to contend (if we may credit Dicæarchus) for the prize of wrestling among boys at the Isthmian festival. His literary training was commenced under a schoolmaster named Dionysius, and pursued under Draco, a celebrated teacher of music in the large sense then attached to that word. He is said to have displayed both diligence and remarkable quickness of apprehension, combined too with the utmost gravity and modesty. He not only acquired great familiarity with the poets, but composed poetry of his own—dithyrambic, lyric, and tragic; and he is even reported to have prepared a tragic tetralogy, with the view of competing for victory at the Dionysian festival. We are told that he burned these poems, when he attached himself to the society of Socrates. No compositions in verse remain under his name, except a few epigrams—amatory, affectionate, and of great poetical beauty. But there is ample proof in his dialogues that the cast of his mind was essentially poetical. Many of his philosophical speculations are nearly allied to poetry and acquire their hold upon the mind rather through imagination and sentiment than through reason or evidence.

According to Diogenes (who on this point does not cite his authority), it was about the twentieth year of Plato's age (407 B.C.) that his acquaintance with Socrates began. It may possibly have begun earlier, but certainly not later, since at the time of the conversation (related by Xenophon) between Socrates and Plato's younger brother Glaucon, there was already a friendship established between Socrates and Plato; and that time can hardly be later than 406 B.C., or the beginning of 405 B.C. From 406 B.C. down to 399 B.C., when Socrates was tried and condemned, Plato seems to have remained in friendly relation and society with him, a relation perhaps interrupted during the severe political struggles between 405 B.C. and 403 B.C., but revived and strengthened after the restoration of the democracy in the last-mentioned year.

Whether Plato ever spoke with success in the public assembly we do not know; he is said to have been shy by nature, and his voice was thin and feeble, ill adapted for the Pnyx. However, when the oligarchy of Thirty was established, after the capture and subjugation of Athens, Plato was not only relieved from the necessity of addressing the assembled people, but also obtained additional facilities for rising into political influence, through Critias (his near relative) and Charmides, leading men among the new oligarchy. Plato affirms that he had always disapproved the antecedent democracy, and that he entered on the new scheme of government with full hope of seeing justice and wisdom predominant. He was soon undeceived. The government of the Thirty proved a sanguinary and rapacious tyranny, filling him with disappointment and disgust. He was especially revolted by their treatment of Socrates, whom they not only interdicted from continuing his habitual colloquy with young men, but even tried to implicate in nefarious murders, by ordering him along with others to arrest Leon the Salaminian, one of their intended victims; an order which Socrates, at the peril of his life, disobeyed.

Thus mortified and disappointed, Plato withdrew from public functions. What part he took in the struggle between the oligarchy and its democratical assailants under Thrasybulus we are not informed. But when the democracy was reestablished his political ambition revived and he again sought to acquire some active influence on public affairs. Now, however, the circumstances had become highly unfavorable to him. The name of his deceased relative, Critias, was generally abhorred, and he had no powerful partisans among the popular leaders. With such disadvantages, with anti-democratical sentiments, and with a thin voice, we cannot wonder that Plato soon found public life repulsive, though he admits the remarkable moderation displayed by the restored Demos. His repugnance was aggravated to the highest pitch of grief and indignation by the trial and condemnation of Socrates (399 B.C.) four years after the renewal of the democracy. At that moment doubtless the Socratic men or companions were unpopular in a body. Plato, after having yielded his best sympathy and aid at the trial of Socrates, retired along with several others of them to Megara. He made up his mind that for a man of his views and opinions it was not only unprofitable, but also unsafe, to embark in active public life, either at Athens or in any other Grecian city. He resolved to devote himself to philosophical speculation and to abstain from practical politics, unless fortune, should present to him some exceptional case of a city prepared to welcome and obey a renovator upon exalted principles.

At Megara Plato passed, some time with the Megarian Eucleides, his fellow-disciple in the society of Socrates and the founder of what is termed the Megaric school of philosophers. He next visited Cyrênê, where he is said to have become acquainted with the geometrician Theodorus and to have studied geometry under him. From Cyrênê he proceeded to Egypt, interesting himself much in the antiquities of the country as well as in the conversation of the priests. In or about 394 B.C., if we may trust the statement of Aristoxenus about the military service of Plato at Corinth, he was again at Athens. He afterward went to Italy and Sicily, seeking the society of the Pythagorean philosophers, Archytas, Echecrates, Timæus, etc., at Tarentum and Locri, and visiting the volcanic manifestations of Ætna. It appears that his first visit to Sicily was made when he was about forty years of age, which would be 387 B.C. Here he made acquaintance with the youthful Dion, over whom he acquired great intellectual ascendancy. By Dion Plato was prevailed upon to visit the elder Dionysius at Syracuse; but that despot, offended by the free spirit of his conversation and admonitions, dismissed him with displeasure, and even caused him to be sold into slavery at Ægina on his voyage home. Though really sold, however, Plato was speedily ransomed by friends. After farther incurring some risk of his life as an Athenian citizen, in consequence of the hostile feelings of the Æginetans, he was conveyed away safely to Athens, about 386 B.C.

It was at this period, about 386 B.C., that the continuous and formal public teaching of Plato, constituting as it does so great an epoch in philosophy, commenced. But I see no ground for believing, as many authors assume, that he was absent from Athens during the entire interval between 399-386 B.C.

The spot selected by Plato for his lectures or teaching was a garden adjoining the precinct sacred to the hero Hecademus or Acedêmus, distant from the gate of Athens called Dipylon somewhat less than a mile, on the road to Eleusis, toward the north. In this precinct there were both walks, shaded by trees, and a gymnasium for bodily exercise; close adjoining, Plato either inherited or acquired a small dwelling-house and garden, his own private property. Here, under the name of the Academy, was founded the earliest of those schools of philosophy, which continued for centuries forward to guide and stimulate the speculative minds of Greece and Rome.

We have scarce any particulars respecting the growth of the School of Athens from this time to the death of Plato, in 347 B.C. We only know generally that his fame as a lecturer became eminent and widely diffused; that among his numerous pupils were included Speusippus, Xenocrates, Aristotle, Demosthenes, Hyperides, Lycurgus, etc.; that he was admired and consulted by Perdiccas in Macedonia, and Dionysius at Syracuse; that he was also visited by listeners and pupils from all parts of Greece.

It was in the year 367-366 that Plato was induced, by the earnest entreaties of Dion, to go from Athens to Syracuse, on a visit to the younger Dionysius, who had just become despot, succeeding to his father of the same name. Dionysius II., then very young, had manifested some disposition toward philosophy and prodigious admiration for Plato, who was encouraged by Dion to hope that he would have influence enough to bring about an amendment or thorough reform of the government at Syracuse. This ill-starred visit, with its momentous sequel, has been described in my "History of Greece." It not only failed completely, but made matters worse rather than better; Dionysius became violently alienated from Dion and sent him into exile. Though turning a deaf ear to Plato's recommendations, he nevertheless liked his conversation, treated him with great respect, detained him for some time at Syracuse, and was prevailed upon, only by the philosopher's earnest entreaties, to send him home. Yet in spite of such uncomfortable experience, Plato was induced, after a certain interval, again to leave Athens and pay a second visit to Dionysius, mainly in hopes of procuring the restoration of Dion. In this hope, too, he was disappointed, and was glad to return, after a longer stay than he wished, to Athens.

The visits of Plato to Dionysius were much censured and his motives misrepresented by unfriendly critics, and these reproaches were still further embittered by the entire failure of his hopes. The closing years of his long life were saddened by the disastrous turn of events at Syracuse, aggravated by the discreditable abuse of power and violent death of his intimate friend, Dion, which brought dishonor both upon himself and upon the Academy. Nevertheless, he lived to the age of eighty, and died in 348-347 B.C., leaving a competent property, which he bequeathed by a will still extant. But his foundation, the Academy, did not die with him. It passed to his nephew Speusippus, who succeeded him as teacher, conductor of the school, or scholarch, and was himself succeeded after eight years by Xenocrates of Chalcêdon; while another pupil of the Academy, Aristotle, after an absence of some years from Athens, returned thither and established a school of his own at the Lyceum, at another extremity of the city.

The latter half of Plato's life in his native city must have been one of dignity and consideration, though not of any political activity. He is said to have addressed the Dicastery as an advocate for the accused general Chabrias; and we are told that he discharged the expensive and showy functions of Choregus with funds supplied by Dion. Out of Athens also his reputation was very great. When he went to the Olympic festival of B.C. 360 he was an object of conspicuous attention and respect; he was visited by hearers, young men of rank and ambition, from the most distant Hellenic cities.

Such is the sum of our information respecting Plato. Scanty as it is we have not even the advantage of contemporary authority for any portion of it. We have no description of Plato from any contemporary author, friendly or adverse. It will be seen that after the death of Socrates we know nothing about Plato as a man and a citizen, except the little which can be learned from his few epistles, all written when he was very old and relating almost entirely to his peculiar relations with Dion and Dionysius. His dialogues, when we try to interpret them collectively, and gather from them general results as to the character and purposes of the author, suggest valuable arguments and perplexing doubts, but yield few solutions. In no one of the dialogues does Plato address us in his own person. In the Apology alone (which is not a dialogue) is he alluded to even as present; in the Phædon he is mentioned as absent from illness. Each of the dialogues, direct or indirect, is conducted from beginning to end by the persons whom he introduces. Not one of the dialogues affords any positive internal evidence showing the date of its composition. In a few there are allusions to prove that they must have been composed at a period later than others, or later than some given event of known date; but nothing more can be positively established. Nor is there any good extraneous testimony to determine the date of any one among them; for the remark ascribed to Socrates about the dialogue called Lysis (which remark, if authentic, would prove the dialogue to have been composed during the lifetime of Socrates) appears altogether untrustworthy. And the statement of some critics, that the Phædrus was Plato's earliest composition, is clearly nothing more than an inference (doubtful at best, and in my judgment erroneous) from its dithyrambic style and erotic subject.