The Difficult is that which can be done immediately; the Impossible that which takes a little longer.
Perhaps the only true dignity of man is his capacity to despise himself.
Skepticism is the chastity of the intellect...
Eternal vigilance is the price of knowledge.
To be happy you must have taken the measure of your powers, tasted the fruits of your passion, and learned your place in the world.
To know what people really think, pay regard to what they do, rather than what they say.