Nothing is more unworthy of a wise man, or ought to trouble him more, than to have allowed more time for trifling, and useless things, than they deserve.
The true lover of knowledge naturally strives for truth, and is not content with common opinion, but soars with undimmed and unwearied passion till he grasps the essential nature of things.
It was Plato, according to Sosigenes, who set this as a problem for those concerned with these things, through what suppositions of uniform and ordered movements the appearances concerning the movements of the wandering heavenly bodies could be preserved.
By education I mean that training in excellence from youth upward which makes a man passionately desire to be a perfect citizen, and teaches him to rule, and to obey, with justice. This is the only education which deserves the name.