"The true logic of this world is in the calculus of probabilities."

"I have been trying to invent a demon who could violate the second law of thermodynamics, but he keeps getting drunk on entropy."

"It is a good thing to have a great many ideas, and a great many of them bad."

"The mathematical difficulties of the subject are so enormous that it is only by great patience and perseverance that we can hope to overcome them."

"The present state of science is such that we cannot hope to explain all the phenomena of nature by means of a few simple laws."