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.
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.
Everything desires not like but unlike: for example, the dry desires the moist, the cold the hot, the bitter the sweet, the sharp the blunt, the void the full, the full the void, and so of all other things; for the opposite is the food of the opposite, whereas like receives like receives nothing from like.
Too much attention to health is a hindrance to learning, to invention, and to studies of any kind, for we are always feeling suspicious shootings and swimmings in our heads, and we are prone to blame studies from them.
The human race will have no respite from evils until those who are really philosophers acquire political power or until, through some divine dispensation, those who rule and have political authority in the cities become real philosophers.