The contemplation of this undoubted succession and agitation has now urged Anaxagoras to a memorable hypothesis. Obviously the conceptions themselves moved themselves, were not pushed and had no cause of motion outside themselves. Therefore he said to himself, there exists a something which bears in itself the origin and the commencement of motion; secondly, however, he notices that this conception was moving not only itself but also something quite different, the body. He discovers therefore, in the most immediate experience an effect of conceptions upon expansive matter, which makes itself known as motion in the latter. That was to him a fact; and only incidentally it stimulated him to explain this fact. Let it suffice that he had a regulative schema for the motion in the world,--this motion he now understood either as a motion of the true isolated essences through the Conceptual Principle, the Nous, or as a motion through a something already moved. That with his fundamental assumption the latter kind, the mechanical transmission of motions and impacts likewise contained in itself a problem, probably escaped him; the commonness and every-day occurrence of the effect through impact most probably dulled his eye to the mysteriousness of impact. On the other hand he certainly felt the problematic, even contradictory nature of an effect of conceptions upon substances existing in themselves and he also tried therefore to trace this effect back to a mechanical push and impact which were considered by him as quite comprehensible. For the Nous too was without doubt such a substance existing in itself and was characterised by him as a very delicate and subtle matter, with the specific quality of thinking. With a character assumed in this way, the effect of this matter upon other matter had of course to be of exactly the same kind as that which another substance exercises upon a third, _i.e.,_ a mechanical effect, moving by pressure and impact. Still the philosopher had now a substance which moves itself and other things, a substance of which the motion did not come from outside and depended on no one else: whereas it seemed almost a matter of indifference how this automobilism was to be conceived of, perhaps similar to that pushing themselves hither and thither of very fragile and small globules of quicksilver. Among all questions which concern motion there is none more troublesome than the question as to the beginning of motion. For if one may be allowed to conceive of all remaining motions as effect and consequences, then nevertheless the first primal motion is still to be explained; for the mechanical motions, the first link of the chain certainly cannot lie in a mechanical motion, since that would be as good as recurring to the nonsensical idea of the _causa sui._ But likewise it is not feasible to attribute to the eternal, unconditional things a motion of their own, as it were from the beginning, as dowry of their existence. For