No one punishes the evil-doer under the notion, or for the reason, that he has done wrong -- only the unreasonable fury of a beast acts in that way. But he who desires to inflict rational punishment does not retaliate for a past wrong, for that which is done cannot be undone, but he has regard to the future, and is desirous that the man who is punished, and he who sees him punished, may be deterred from doing wrong again.
There should be no element of slavery in learning. Enforced exercise does no harm to the body, but enforced learning will not stay in the mind. So avoid compulsion, and let your children's lessons take the form of play.
The cause of all the blunders committed by man arises from this excessive self-love. For the lover is blinded by the object loved; so that he passes a wrong judgment on what is just, good and beautiful, thinking that he ought always to honor what belongs to himself in preference to truth. For he who intends to be a great man ought to love neither himself nor his own things, but only what is just, whether it happens to be done by himself, or by another.
Physical excellence does not of itself produce a good mind and character: on the other hand, excellence of mind and character will make the best of the physique it is given.
If someone separated the art of counting and measuring and weighing from all the other arts, what was left of each (of the others) would be, so to speak, insignificant.
A library of wisdom, is more precious than all wealth, and all things that are desirable cannot be compared to it. Whoever therefore claims to be zealous of truth, of happiness, of wisdom or knowledge, must become a lover of books.