There is something perhaps a little comic about the idea of spirit photography—something which has thus helped to retard its acceptance. The busy photographer with his camera is so banal, and sometimes so obnoxious, a figure, that to think of him photographing a ghost, or the spirit of a dead relation, verges on bathos or the burlesque. Nevertheless, Nature does not attend to our canons in such matters, and in reality the thing is perfectly feasible and in order. It is well known that the photographic plate is most sensitive to the violet end of the spectrum—that it is this end which has the actinic quality. Moreover, it is known that the actinic quality extends _beyond_ this end, and that there are ultra-violet rays which we cannot see, and which yet are photographically powerful. But the violet rays, as is also well known, are those whose light-waves are smallest—being only about half the size of the red waves;[105] and the ultra-violet rays are still smaller. Consequently, by means of the violet end of the spectrum, information can be got about small objects and infinitesimal details which would elude the more ordinary light. A particle, in fact, may be so small that it would reflect the violet waves, while it would be unable to reflect the red—just as a boat floating on the water will reflect and turn back tiny ripples, while it will simply be tossed about by good-sized waves. Advantage has been taken of this in microscopy, and by ingenious arrangements photographs of objects under the microscope can now be taken by ultra-violet light, so as to show the very minutest details. The application of this to the question before us is clear. If there be a spiritual body, composed of particles so infinitesimal as to be—to begin with—far beyond the limits of visibility, yet gradually condensing and accreting to themselves other and subsidiary particles, there might come a time when such a cloud-form would approach the limit of visibility—the molecules of which it was composed having grown so far. It would be perfectly natural, then, for a body composed of such molecules to come into the region of possible photography in the camera through the ultra-violet rays _before_ it came into the region of visibility to the human eye by means of ordinary light. And thus the seeming paradox may be accounted for—of the appearance of spirit-forms, or even thought-forms, on the photographic plate which are not yet discernible by the eye. At a later stage of materialization the form may of course yield an image both to the eye and to the camera.[106]