The sadistic person is as dependent on the submissive person as the latter is on the former; neither can live without the other. The difference is only that the sadistic person commands, exploits, hurts, humiliates, and that the masochistic person is commanded, exploited, hurt, humiliated. This is a considerable difference in a realistic sense; in a deeper emotional sense, the difference is not so great as that which they both have in common: fusion without integrity.

Ch. 2. - The Art of Loving (1956)