We shall see that this is not so, that it is merely a matter of coming to closer quarters with a conclusion to which we long ago committed ourselves and following it out to its logical consequences. The whole of analytic theory has evolved gradually enough, but the theory of instincts has groped its way forward under greater difficulties than any other part of it. And yet a theory of instincts was so indispensable for the rest that something had to be adopted in place of it. In my utter perplexity at the beginning, I took as my starting-point the poet-philosopher Schiller’s aphorism, that hunger and love make the world go round. Hunger would serve to represent those instincts which aim at preservation of the individual; love seeks for objects: its chief function, which is favoured in every way by nature, is preservation of the species. Thus first arose the contrast between ego instincts and object instincts. For the energy of the latter instincts and exclusively for them I introduced the term libido; an antithesis was thus formed between the ego instincts and the libidinal instincts directed towards objects, _i.e._ love in its widest sense. One of these object instincts, the sadistic, certainly stood out from the rest in that its aim was so very unloving; moreover, it clearly allied itself in many of its aspects with the ego instincts, and its close kinship with instincts of mastery without any libidinal purpose could not be concealed, but these ambiguities could be overcome; in spite of them, sadism plainly belonged to sexual life—the game of cruelty could take the place of the game of love. Neurosis appeared as the outcome of a struggle between the interests of self-preservation and the claims of libido, a struggle in which the ego was victorious, but at the price of great suffering and renunciations.