All learning is in the learner, not the teacher.

My good friend, you are a citizen of Athens, a city which is very great and very famous for its wisdom and power - are you not ashamed of caring so much for the making of money and for fame and prestige, when you neither think nor care about wisdom and truth and the improvement of your soul?

He who is of a calm and happy nature, will hardly feel the pressure of age

But at three, four, five, and even six years the childish nature will require sports; now is the time to get rid of self-will in him, punishing him, but not so as to disgrace him.

Mathematics is like draughts in being suitable for the young, not too difficult, amusing, and without peril to the state.

Man is a prisoner who has no right to open the door of his prison and run away... A man should wait, and not take his own life until God summons him.

[Not enough is known about solid geometry] and for two reasons: in the first place, no government places value on it; this leads to a lack of energy in the pursuit of it, and it is difficult. In the second place, students cannot learn it unless they have a teacher. But then a teacher can hardly be found.