"The most human thing about anyone is a thing he learns and … and earns. It’s a thing he can’t have when he’s very young; if he gets it at all, he gets it after a long search and a deep conviction. After that it’s truly part of him as long as he lives."

“A science fiction story is a story built around human beings, with a human problem and a human solution, which would not have happened at all without its scientific content.”

“You cannot be objective about this because you have been indoctrinated, sermonized, drenched, imbued, inculcated and policed on the matter since first you wore blue booties. You come from a time and place in which the maleness of the male, and the femaleness of the female, and the importance of their difference, were matters of almost total preoccupation.”

“So it was that Lone came to know himself; and like the handful of people who have done so before him he found, at this pinnacle, the rugged foot of a mountain.”

“And Charlie asked questions! His unease had long since disappeared, and two of his most deep-dyed characteristics took over: one, the result of his omnivorous, undisciplined, indefatigable reading and picking of brains; second, the great gaping holes this had left in his considerable body of knowledge. Both appeared far more drastic than he had heretofore known; he knew ever so much more than he knew he knew, and he had between five and seven times as much misinformation and ignorance than he had ever dreamed.”

“If All Men Were Brothers, Would You Let One Marry Your Sister?”

“It's the Simple things that are really effective. Try to remember that.”