Platonist School of Ancient Greek Philosophy Texts
Plato founded the Academy in Athens around 387 BCE, and the institution gave its name to the tradition that followed his work. Unlike the schools that gathered around a founder's personal authority, the Academy endured as an institution, and the name "Platonist" came to cover every later thinker who took Plato's writings as the starting point of philosophy.
A central teaching of that tradition is the existence of the εἶδος or ἰδέα, the look or form of a thing. Beyond the changing, imperfect world given to the senses lies a realm of unchanging realities, and these looks are the proper objects of knowledge: all beautiful things, for instance, share in the look of Beauty itself, while the perceptible world stands as an image of the intelligible one. The human ψυχή is deathless and existed before the body, and it brings an innate familiarity with the looks that inquiry can draw out again. The aim of life is to turn the ψυχή away from bodily concerns and toward contemplation of the looks, culminating in understanding of the look of the Good.
The tradition's history falls into named phases. The Old Academy, led by Plato and his immediate successors Speusippus and Xenocrates, developed his ideas. Around 266 BCE Arcesilaus initiated the Middle Academy, arguing that certainty is unattainable and suspending judgement on every dogmatic claim; Carneades carried this stance into the New Academy. Around 90 BCE Antiochus of Ascalon broke with the sceptical line, claiming to return to the doctrines of Plato and his early successors, and this dogmatic revival continued through the Roman period, in which figures such as Plutarch of Chaeronea were prominent. Aristotle had developed his own philosophy during his years at the Academy before departing from it.
The final major phase was Neoplatonism, which began with Plotinus in the 3rd century CE and was carried forward by his successors Porphyry, Iamblichus, and Proclus. The Neoplatonists elaborated a metaphysical system in which all things flow from a single source, the One. The Platonic school at Athens was closed by imperial order in 529 CE, though philosophical teaching in Plato's name continued elsewhere.