Before I adduce the evidence on this point, however, it may be well to illustrate the fact that there is no inherent absurdity in the idea, as many might suppose. Of course the spiritual body would have to be material enough to reflect light waves, but where is the evidence that it is not? There seems to be much evidence, on the contrary, that it _is_. It must be remembered that the camera will disclose innumerable things quite invisible to the naked eye, or even to the eye aided by the strongest glasses or telescopes. Normally, we can see but a few hundred stars in the sky; with the aid of telescopes, we can see many thousand; but the photographic camera discloses more than _twenty million_! Here, then, is direct evidence that the camera can observe things which we cannot see; and, indeed, this whole process of sight or "seeing" is a far more complicated one than most persons imagine. As Sir Oliver Lodge has pointed out, there is no reason why we should not be enabled to photograph a spirit, when we can photograph an image in a mirror--which is composed simply of vibrations, and reflected vibrations at that! We are a long way from the tangible thing, in such a case; and yet we are enabled to photograph it with an ordinary camera. Any disturbance in the ether we should be enabled to photograph likewise--if only we had delicate enough instruments, and if the "conditions" for the experiment were favourable. The phenomena of spirit-photography, and especially the experiments of Dr. Baraduc, to which I shall presently refer, would seem to indicate this.