The production of the symmetrical forms of organised beings, though not of course due to a turning over of bodies of any appreciable size in four-dimensional space, can well be imagined as due to a disposition in that manner of the smallest living particles from which they are built up. Thus, not only electricity, but life, and the processes by which we think and feel, must be attributed to that region of magnitude in which four-dimensional movements take place. I do not mean, however, that life can be explained as a four-dimensional movement. It seems to me that the whole bias of thought, which tends to explain the phenomena of life and volition, as due to matter and motion in some peculiar relation, is adopted rather in the interests of the explicability of things than with any regard to probability. Of course, if we could show that life were a phenomenon of motion, we should be able to explain a great deal that is at present obscure. But there are two great difficulties in the way. It would be necessary to show that in a germ capable of developing into a living being, there were modifications of structure capable of determining in the developed germ all the characteristics of its form, and not only this, but of determining those of all the descendants of such a form in an infinite series. Such a complexity of mechanical relations, undeniable though it be, cannot surely be the best way of grouping the phenomena and giving a practical account of them. And another difficulty is this, that no amount of mechanical adaptation would give that element of consciousness which we possess, and which is shared in to a modified degree by the animal world. In those complex structures which men build up and direct, such as a ship or a railway train (and which, if seen by an observer of such a size that the men guiding them were invisible, would seem to present some of the phenomena of life) the appearance of animation is not due to any diffusion of life in the material parts of the structure, but to the presence of a living being. The old hypothesis of a soul, a living organism within the visible one, appears to me much more rational than the attempt to explain life as a form of motion. And when we consider the region of extreme minuteness characterised by four-dimensional motion the difficulty of conceiving such an organism alongside the bodily one disappears. Lord Kelvin supposes that matter is formed from the ether. We may very well suppose that the living organisms directing the material ones are co-ordinate with them, not composed of matter, but consisting of etherial bodies, and as such capable of motion through the ether, and able to originate material living bodies throughout the mineral.