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

"The true Logic for this world is the Calculus of Probabilities, which takes account of the magnitude of the probability."

"The only way of discovering the extent of the laws of nature is to try to transcend them."

"I have no doubt that there are many persons who would be very glad to get rid of the ether."