"Every existence above a certain rank has its singular points; the higher the rank the more of them. At these points, influences whose physical magnitude is too small to be taken account of by a finite…"

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

"I have been trying to think what is the difference between an experiment and an experience."

"The velocity of light is a quantity of which we have now a more accurate knowledge than of any other physical constant."

"The only way to avoid error is to have no ideas at all."