"Silence is a source of great strength."

"Knowing yourself is the beginning of all wisdom."

"He who has a why to live can bear almost any how."

"The mind is everything. What you think you become."

"By three methods we may learn wisdom: first, by reflection, which is noblest; se..."

"A wise man can learn more from a foolish question than a fool can learn from a w..."

"The fool doth think he is wise, but the wise man knows himself to be a fool."

"The only thing I know is that I know nothing."