Instead of the opposition between the two classes of instincts let us consider the polarity of love and hate. (There is no difficulty in finding a representative of Eros; but we must be grateful that we can find a representative of the elusive death-instinct in the instinct of destruction, for which hate points the way.) Now, clinical observation shows not only that love is with unexpected regularity accompanied by hate (ambivalence), and not only that in human relationships hate is frequently a forerunner of love, but also that in many circumstances hate changes into love and love into hate.
