"The tears of the world are a constant quantity. For every one who begins to weep, somewhere else another stops. The same is true of the laughter."

"Act as if what you do makes a difference. It does."

"The practical value of a truth is its truth."

"The world is a bad master, and it does not pay to serve it."

"Man, biologically considered, and whatever else he may be into the bargain, is the most formidable of all the beasts of prey, and, indeed, the only one that preys systematically on its own species."