Philosophy starts with doubt and loves only truth.

Our duty is to be useful, not according to our desires but according to our powers.

Heroism is the brilliant triumph of the soul over the flesh - over fear...Heroism is the dazzling and glorious concentration of courage.

An error is the more dangerous in proportion to the degree of truth which it contains.

Man is a willful and covetous animal, who makes use of his intellect to satisfy his inclinations, but who cares nothing for truth, who rebels against personal discipline, who hates disinterested thought and the idea of self-education. Wisdom offends him, because it rouses in him disturbance and confusion, and because he will not see himself as he is.

A belief is not true simply because it is useful.

There is no respect for others without humility in one's self.