Trees and fields tell me nothing: men are my teachers.
They ought to be gentle to their friends and dangerous to their enemies.
The right question is usually more important than the right answer.
To be conquered by yourself is of all things most shameful and vile.
Don't quarrel with your parents even if you are on the right.
Seven years of silent inquiry are needful for a man to learn the truth, but fourteen in order to learn how to make it known to his fellow-men.