Theaetetus

From Ancient Greek Θεαίτητος (Theaítētos); the mathematician is the eponym of the dialogue and the lunar crater.

Theaetetus

1. A classical Greek mathematician credited with proving that there are precisely five regular convex polyhedra.
2. A later middle dialogue of Plato concerning epistemology.
3. A lunar impact crater 2.8 kilometres in depth and 25 kilometres in diameter, located southeast of the crater Cassini, near the eastern edge of Mare Imbrium.

• 1962, Norman Malcolm; Dreaming; chapter sixteen: “Dreams and Scepticism”, page 101 (1977 paperback reprint; Routledge & Kegan Paul; ISBN 0‒7100‒3836‒4 (c), 0‒7100‒8434‒X (p)):

  Socrates puts to Theætetus the question, ‘What evidence could be appealed to, supposing we were asked at this very moment whether we are asleep or awake?’, and the latter replies, ‘Indeed, Socrates, I do not see by what evidence it is to be proved; for the two conditions correspond in every circumstance like exact counterparts’ (Plato, (2), 158b–158c).