One view deprives the problem of propagation of its mysterious attraction by representing it as part of the phenomenon of growth (multiplication by division, germination, budding). The arising of propagation by means of germ cells sexually differentiated might be conceived, in accordance with the sober Darwinian mode of thought, as a way of maintaining and utilising for further development the advantage of the amphimixis which resulted in the first instance from the fortuitous conjugation of two protozoa.[34] ‘Sex’ would not thus be of very ancient origin and the extraordinarily powerful instincts which aim at bringing about sexual union would thereby repeat something which once chanced to happen and since became established as being advantageous. The same question now recurs as arose in respect of death—namely, whether the protozoa can be credited with anything beyond what they exhibit, and whether we may assume that forces and processes which become perceptible only in the case of the higher animals did first arise in the more primitive. For our purpose the view of sexuality mentioned above helps very little. The objection may be raised against it that it presupposes the existence of life-instincts as already operative in the simplest forms of life, for otherwise conjugation, which works against the expiration of life and makes the task of dying harder, would not have been retained and elaborated, but would have been avoided. If, then, we are not to abandon the hypothesis of death-instincts maintained, we must associate them with life-instincts from the beginning. But we must admit that we are working here at an equation with two unknown quantities. Anything else that science can tell us of the origin of sexuality amounts to so little that this problem may be likened to an obscurity into which not even the ray of an hypothesis has penetrated. In quite another quarter, however, we encounter such an hypothesis, but it is of so fantastic a kind—assuredly a myth rather than a scientific explanation—that I should not venture to bring it forward if it did not exactly fulfil the one condition for the fulfilment of which we are labouring. That is to say, it derives an instinct from the _necessity for the reinstatement of an earlier situation_.