The question has led to a number of seemingly irresolvable scholarly disputes.
At least one important ancient source, Aristotle, suggests that at least some of the doctrines Plato puts into the mouth of the "Socrates" of the "early" or "Socrates" dialogues are the very ones espoused by the historical Socrates.
Dion subsequently gathered an army of mercenaries and invaded his own homeland.
Plato, perhaps now completely disgusted with politics, returned to his beloved Academy, where he lived out the last thirteen years of his life. His grave, however, has not yet been discovered by archeological investigations. There can be no doubt that Plato was also strongly influenced by Parmenides and Zeno (both of Elea), in Plato's theory of the Forms, which are plainly intended to satisfy the Parmenidean requirement of metaphysical unity and stability in knowable reality.
According to Diogenes, Plato was buried at the school he founded (D. Aristotle and Diogenes agree that Plato had some early association with either the philosophy of Heraclitus of Ephesus, or with one or more of that philosopher's followers (see Aristotle Metaph. Parmenides and Zeno also appear as characters in his dialogue, the He mixed together in his works the arguments of Heracleitus, the Pythagoreans, and Socrates. 3.8) A little later, Diogenes makes a series of comparisons intended to show how much Plato owed to the comic poet, Epicharmus (3.9-3.17).
Nonetheless, it is plain that no influence on Plato was greater than that of Socrates.
This is evident not only in many of the doctrines and arguments we find in Plato's dialogues, but perhaps most obviously in Plato's choice of Socrates as the main character in most of his works.
It has frequently been assumed that if we can establish a relative chronology for when Plato wrote each of the dialogues, we can provide some objective test for the claim that Plato represented Socrates more accurately in the earlier dialogues, and less accurately in the later dialogues.
In antiquity, the ordering of Plato's dialogues was given entirely along thematic lines.
According to the Plato counted Socrates "the justest man alive" (324e).
According to Diogenes Laertius, the respect was mutual (3.5). Whether or not any of these stories is true, there can be no question of Plato's mastery of dialogue, characterization, and dramatic context.
Later (at 3.6), Diogenes says that Plato was twenty-eight when Socrates was put to death (in 399), which would, again, put his year of birth at 427. Both sides of the family claimed to trace their ancestry back to Poseidon (D. We can be confident that Plato also had two older brothers, Glaucon and Adeimantus, and a sister, Potone, by the same parents (see D. "Plato" seems to have started as a nickname (for or "broad"), perhaps first given to him by his wrestling teacher for his physique, or for the breadth of his style, or even the breadth of his forehead (all given in D. Plato occasionally mentions Egypt in his works, but not in ways that reveal much of any consequence (see, for examples, According to the account given there, Plato first went to Italy and Sicily when he was "about forty" (324a). (This is where we get our word, "academic." The Academy got its name from its location, a grove of trees sacred to the hero Academus—or Hecademus [see D. 3.7]—a mile or so outside the Athenian walls; the site can still be visited in modern Athens, but visitors will find it depressingly void of interesting monuments or features.) Except for two more trips to Sicily, the Academy seems to have been Plato's home base for the remainder of his life.
In spite of the confusion, the dates of Plato's life we gave above, which are based upon Eratosthenes' calculations, have traditionally been accepted as accurate. According to Diogenes, whose testimony is notoriously unreliable, Plato's parents were Ariston and Perictione (or Potone—see D. While he stayed in Syracuse, he became the instructor to Dion, brother-in-law of the tyrant Dionysius I. The first of Plato's remaining two Sicilian adventures came after Dionysius I died and his young son, Dionysius II, ascended to the throne. Dionysius then summoned Plato, but wished for Dion to wait a while longer.
Because they tended to distract us into accepting less than our highest potentials, however, Plato mistrusted and generally advised against physical expressions of love. These dates, however, are not entirely certain, for according to Diogenes Laertius (D. If Plato's date of death is correct in Apollodorus' version, Plato would have been born in 430 or 431. His stepfather Pyrilampes was said to have been a close associate of Pericles, when he was the leader of the democratic faction. When Socrates died, Plato left Athens, staying first in Megara, but then going on to several other places, including perhaps Cyrene, Italy, Sicily, and even Egypt.