Full Idea
The slave boy's knowledge of geometry will not come from teaching but from questioning; he will recover it for himself, and the spontaneous recovery of knowledge that is in him is recollection.
Gist of Idea
The slave boy learns geometry from questioning, not teaching, so it is recollection
Source
Plato (Meno [c.376 BCE], 85d)
Book Reference
Plato: 'Complete Works', ed/tr. Cooper,John M. [Hackett 1997], p.886
A Reaction
Of course, if maths and geometry are huge tautological axiom systems, we would expect to be able to derive them (with hints from a teacher) entirely from their axioms. It is not clear why we might be able to derive the truths of all nature a priori.