Reason has never had the power to define good and evil, or even to distinguish between good and evil, even approximately
 Fyodor Dostoyevsky, Demons (1872). copy citation

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Author Fyodor Dostoyevsky
Source Demons
Topic evil power
Date 1872
Language English
Reference
Note Translated by Constance Garnett in 1916
Weblink http://www.gutenberg.org/files/8117/8117-h/8117-h.htm

Context

“Every people has its own conception of good and evil, and its own good and evil. When the same conceptions of good and evil become prevalent in several nations, then these nations are dying, and then the very distinction between good and evil is beginning to disappear. Reason has never had the power to define good and evil, or even to distinguish between good and evil, even approximately; on the contrary, it has always mixed them up in a disgraceful and pitiful way; science has even given the solution by the fist. This is particularly characteristic of the half-truths of science, the most terrible scourge of humanity, unknown till this century, and worse than plague, famine, or war.” source