Robert Louis Stevenson: Duality of Man

I learned to recognize the thorough and primitive duality of man; I saw that, of the two natures that contended in the field of my consciousness, even if I could rightly be said to be either, it was only because I was radically both.
― Robert Louis Stevenson, The Strange Case of Dr. Jekyll and Mr. Hyde

With every day, and from both sides of my intelligence, the moral and the intellectual, I thus drew steadily nearer to the truth, by whose partial discovery I have been doomed to such a dreadful shipwreck: that man is not truly one, but truly two.
― Robert Louis Stevenson, The Strange Case of Dr. Jekyll and Mr. Hyde