"In the present state of science, it would be a rash thing to assert that any one physical constant is absolutely constant."

"It is a perfect pleasure to think of anything that is not connected with the examination."

"Mathematicians my flatter themselves that they possess new ideas which mere human language is as yet unable to express."

"The human mind is in a state of perpetual oscillation between the actual and the possible."

"The human mind is seldom satisfied, and is certainly never exercising its highest functions, when it is doing the work of a calculating machine."