Duality quotes from the text:
It was on the moral side, and in my own person, that I learned to recognise 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; and from an early date . . . I had learned to dwell with pleasure, as a beloved daydream, on the thought of the separation of these elements.
But I was still cursed with my duality of purpose; and as the first edge of my penitence wore off, the lower side of me, so long indulged, so recently chained down, began to growl for licence. Not that I dreamed of resuscitating Hyde; . . . no, it was in my own person that I was once more tempted to trifle with my conscience. . . .
Dr. Jekyll and Mr. Hyde