The greatest obstacle to being heroic is the doubt whether one may not be going to prove one's self a fool; the truest heroism is to resist the doubt; and the profoundest wisdom, to know when it ought to be resisted, and when it be obeyed.

"The only way to deal with an unfree world is to become so absolutely free that your very existence is an act of rebellion."

Contemplating the weaknesses of others is easy； contemplating the weaknesses in yourself is hard， but it pays a much higher reward.

The interest of the behaviorist in man's doings is more than the interest of the spectator—he wants to control man's reactions as physical scientists want to control and manipulate other natural phenomena.