James Clerk Maxwell — "The properties of the ether, if it exists, are certainly very remarkable."

"The opinion seems to have got abroad, that in a few years all the great physical constants will have been approximately estimated, and that the only occupation which will then be left to men of scienc…"

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

"The mind can only attend to one thing at a time."

"If I am not mistaken, there is a good deal of nonsense in the world."

"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."