“That’s a cynical viewpoint,” Horn said slowly. “I’m an old man. I can afford no longer the luxury of ideals. If I am to achieve results recognizable… - Jack Williamson

“I’m not a religious man, Mr. Barbee—I reject the supernatural, and my own rational philosophy is founded on proven science. But I still believe in hell.”
The dark man smiled.
“For every man manufactures his own private hell and peoples it with demons of his own creation, to torment him for his own secret sins, imagined or real. It’s my business to explore those personal hells and expose their demons for what they are. Usually they turn out to be much less terrifying than they seem.”

Two weeks passed, by the time of the ship—physiological time, that measured by heartbeats and all bodily rhythms, in which the span of life moved relentlessly toward its end, regardless of motion backward or forward along the time dimension.

Human knowledge is never entirely consistent or complete, because the human brain is only a crude and transient mass of watery cells, error-prone and glacier-slow.