That had not been the first time nor had it been the last, but all the years of killing boiled down in essence to that single moment — not the time that came after, but that long and terrible instant when he had watched the lines of men purposefully striding up the slope to kill him.Somewhere, he thought, on the long backtrack of history, the human race had accepted an insanity for a principle and had persisted in it until today that insanity-turned-principle stood ready to wipe out, if not the race itself, at least all of those things, both material and immaterial, that had been fashioned as symbols of humanity through many hard-won centuries.
Clifford D. Simak