In the Meno and Phaedo, Socrates argues that the soul, being immortal, has seen all things before birth, and that learning is recollection. He demonstrates by leading a slave boy to discover a geometrical truth by questioning alone. The teaching implies that knowledge of the Forms lies within.
Anamnesis
Recollection: Plato’s teaching that learning is remembering what the soul knew before birth.
Also: recollection