"The truly wise man is he who knows that he knows nothing."

"Thinking is easy, acting is difficult, and to put one's thoughts into action is the most difficult thing in the world."

"Talent develops in tranquility, character in the full current of human life."

"The true man of science is he who gives importance to the little, because he sees the greatness of the great in it."

"Die Botschaft hör ich wohl, allein mir fehlt der Glaube."