It has often been argued, in fact, that mankind lost the happiness characteristic of his fellow-animals when he acquired self-consciousness. This is in fact the meaning of the legend of "The Fall." We have become as gods, knowing good and evil, and the price is that we live by labour, and—"In his eyes foreknowledge of death."
Crowley, Aleister  (1970). "A Heroin Heroine", Diary of a Drug Fiend, 7th American edition printing, 1985, York Beach, Maine: Samuel Weiser, 71-72. ISBN 0-87728-146-7.
This is particularly interesting to me in that I have been thinking quite a bit lately about the dichotomy of good and evil, and whether this has any existence at all outside the mind; i.e., I begin to suspect that, as the Bard puts it in the mouth of Hamlet, "there is nothing either good / or bad but thinking makes it so." (II:ii) To do otherwise, so far as I can tell, requires a reification of opinion that I find philosophically untenable.