“Beyond his own sure knowledge, he had not a shred of proof.”
“The Sitters” (p. 90)
Short Fiction, Skirmish (1977)
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Clifford D. Simak 137
American writer, journalist 1904–1988Related quotes

Jimmy Page – Guitarist from Led Zeppelin/The Yardbirds/solo from the BBC Documentary "Everybody Here Wants You"

“I don't believe Fermat had a proof. I think he fooled himself into thinking he had a proof.”
Nova Interview
Knowing Yourself: The True in the False (1996)
Context: You think: you become that thought. And consciousness, or the state of pure awareness, is lost. The highest knowledge man can possess is that which is true in his own experience. If his experience is limited, so is his knowledge and he behaves accordingly.

“No man's knowledge here can go beyond his experience.”
Book II, Ch. 1, sec. 19
An Essay Concerning Human Understanding (1689)

“The chief proof of man's real greatness lies in his perception of his own smallness.”
Source: The Sign of Four

“Knowledge once gained casts a faint light beyond its own immediate boundaries.”
On the Methods and Tendencies of Physical Investigation, p. 7.
Scientific addresses (1870)