" Malygris turned to the viper and spoke in a tone of melancholy reproof: “Why did you not warn me?” “Would the warning have availed?” was the counter-question. “All knowledge was yours, Malygris, excepting this one thing; and in no other way could you have learned it.” “What thing?” queried the magician. “I have learned nothing except the vanity of wisdom, the impotence of magic, the nullity of love, and the delusiveness of memory… Tell me, why could I not recall to life the same Nylissa whom I knew, or thought I knew?” “It was indeed Nylissa whom you summoned and saw,” replied the viper. “Your necromancy was potent up to this point; but no necromantic spell could recall for you your own lost youth or the fervent and guileless heart that loved Nylissa, or the ardent eyes that beheld her then. This, my master, was the thing that you had to learn. "
― Clark Ashton Smith , The End of the Story