"One must be a complete person to be able to love another completely."

"The beautiful is a manifestation of secret laws of nature, which, but for this appearance, would have remained hidden from us."

"A clever man commits no minor blunders."

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

"Grau, teurer Freund, ist alle Theorie, und grün des Lebens goldner Baum."