At this point opportunity offers of reviewing the gradual development of our Libido theory. The analysis of the transference-neuroses forced on our notice in the first place the opposition between ‘sexual instincts’ which are directed towards an object and other instincts which we only imperfectly discerned and provisionally described as ‘ego-instincts’. Among the latter those which subserve the self-preservation of the individual had the first claim for recognition. What other distinctions were to be made, it was impossible to say. No knowledge would have been so important for the establishment of a sound psychology as some approximate understanding of the common nature and possible differences of the instincts. But in no department of psychology did one grope more in the dark. Everyone posited as many instincts or ‘fundamental instincts’ as he pleased, and contrived with them just as the ancient Greek philosophers did with their four elements: earth, air, fire and water. Psycho-Analysis, which could not dispense with some kind of hypothesis as to the instincts, adhered to begin with to the popular distinction, typically represented by the phrase ‘hunger and love’. It was at least no new arbitrary creation. With this one adequately covered a considerable distance in the analysis of the psychoneuroses. The conception of ‘sexuality’—and therewith that of a sexual instinct—certainly had to Be extended, till it included much that did not come into the category of the function of propagation, and this led to outcry enough in a severe and superior or merely hypocritical world.