Plato's Academy: The Institution Plato Founded, and What Became of It

The institution Plato founded was the Academy — a school of philosophy and mathematics established in Athens around 387 BC, which he led until his death forty years later and which outlived him by nearly three centuries. It is the ancestor of every “academy” since, and arguably of the research university itself. It was also, in almost every respect, unlike what the word now suggests.

Where the name comes from

The Academy was not named for learning. It was named for a place: a grove and public gymnasium about a mile north-west of the Athenian walls, sacred to a local hero, Akademos (or Hekademos), and shaded by olive trees and plane trees that Athenians had walked among for generations. Plato bought a small property beside the public grove (Diogenes Laertius III.7) and began teaching there after returning from his first journey to Italy and Sicily. The school took the name of the park. So did every academy afterwards.

What it was — and wasn’t

It charged no fees. That alone separated it from the sophists, who taught rhetoric for money and whom Plato spent his life attacking. It awarded no degrees, set no curriculum in the modern sense, and had no formal enrolment. The best guess of ancient historians is that it was organised as a thiasos — a religious association dedicated to the Muses, which gave a private group of friends a legal shape and a shared shrine.

What it was, in practice, was a community of people who lived near one another, ate together, and spent their days in conversation and research under a leader who set the questions. Teaching was by dialogue — the method Plato learned from Socrates and dramatised in his written works — supplemented by lectures. One of those became notorious: Aristoxenus (Harmonics II.30) reports that Plato advertised a public lecture “On the Good,” and that the audience, expecting advice on wealth and happiness, walked out when it turned out to be about mathematics and the One.

The inscription said to have hung over the door — “Let no one ignorant of geometry enter” — is first recorded in commentators writing some nine centuries after Plato’s death. It may be an invention. It is nonetheless a fair summary of the place.

What was studied there

The best evidence for the Academy’s programme is the one Plato prescribes for his future philosopher-rulers in Republic VII (521c–531c): arithmetic, plane geometry, solid geometry, astronomy, and harmonics, in that order, each pursued not for its uses but because it turns the mind from what changes toward what does not (527b) — the Forms. Only after ten years of this does dialectic, philosophy proper, begin.

The Academy’s mathematical output suggests the programme was real. Theaetetus, who gives his name to a dialogue, classified the irrational magnitudes; Eudoxus of Cnidus, the finest mathematician of the age, developed the theory of proportion later preserved in Euclid and the first geometrical model of planetary motion; Menaechmus discovered the conic sections. The astronomical brief Plato is said to have set — to find the uniform circular motions that “save the appearances” of the wandering planets — was the research question of Greek astronomy for centuries. Pythagorean mathematics, which Plato had met in Italy, was the seed; the Academy was where it became a discipline.

Who was there

Aristotle arrived at seventeen, in 367 BC, and stayed for twenty years — as student, then colleague, then increasingly as critic. He left only when Plato died and the headship passed not to him but to Plato’s nephew Speusippus. Xenocrates succeeded Speusippus. Heraclides of Pontus proposed that the earth rotates. Philip of Opus edited Plato’s last work, the Laws, from the wax tablets it was left on.

Two women are recorded among the students — Axiothea of Phlius, who is said to have attended dressed as a man, and Lastheneia of Mantinea (Diogenes Laertius III.46). In fourth-century Athens, where women had no public life at all, this is remarkable, and it matches the Republic‘s argument that the guardians’ education should be open to both sexes.

What became of it

The school Plato founded lasted, under a succession of heads, until the first century BC — but it did not stay Plato’s school. Around 266 BC Arcesilaus turned the Academy sceptical: on his reading, Socrates’ “I know that I know nothing” was the whole of the inheritance, and the Academy’s task was to argue against every dogma, including Plato’s. This “Middle” and then “New” Academy, under Carneades, was the great sceptical tradition of antiquity — the position Cicero, who studied there, adopted.

The grove itself died in war. When Sulla besieged Athens in 86 BC he cut down the trees of the Academy for siege engines (Plutarch, Sulla 12). The institution effectively ended with that generation; its last head, Antiochus of Ascalon, taught elsewhere. The frequently repeated claim that “Plato’s Academy was closed by the Emperor Justinian in 529 AD” refers to a different institution — the Neoplatonic school of Athens, founded in the fifth century AD, which claimed the name and the succession but had no continuity with the grove.

Why it mattered

Plato did not invent the school; the Pythagoreans had communities before him, and the sophists had classes. What he invented was the idea that knowledge should be pursued collectively, for its own sake, over generations, in a place set aside for it — and that the training for it should be long, mathematical, and free. Aristotle’s Lyceum copied the model; the libraries and museums of Alexandria scaled it; the medieval university inherited it; the word survives in every academy, academic, and academy award. When we ask why education was so important to Plato, the Academy is the answer he gave in stone and olive trees rather than in argument.