“Most areas of intellectual life have discovered the virtues of speculation, and have embraced them wildly. In academia, speculation is usually dignified as theory.”

“Yet, as has been said of him before, no theory of life seemed to him to be of any importance compared with life itself. He felt keenly conscious of how barren all intellectual speculation is when separated from action and experiment. He knew that the senses, no less than the soul, have their spiritual mysteries to reveal.”

“My science is based in voraciously wandering fact, luscious speculation, and spontaneous theory with a dash of prevarication. All of which are most likely to come true.”

“This was the very limit beyond which none of them had ever speculated, or even known that there was any speculation to be done.”

“Books appear to be the most immediate instruments of speculative delight.”

“In practical life we are compelled to follow what is most probable ; in speculative thought we are compelled to follow truth.”