Full Idea
Geometry can attract the mind towards truth. It can produce philosophical thought, in the sense that it can reverse the midguided downwards tendencies we currently have.
Gist of Idea
Geometry can lead the mind upwards to truth and philosophy
Source
Plato (The Republic [c.371 BCE], 527b)
Book Reference
Plato: 'Republic', ed/tr. Waterfield,Robin [OUP 1993], p.258
A Reaction
Hence the Academy gate bore the inscription "Let no one enter here who is ignorant of geometry". He's not necessarily wrong. Something in early education must straighten out some of the kinks in the messy human mind.