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

"The mind of man is like a mirror, which reflects the images of things, but does not always reflect them truly."

"At quite uncertain times and places, The atoms left their heavenly path, And by fortuitous embraces, Engendered all that being hath. And though they seem to cling together, And form 'associations' her…"

"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."