I have mentioned these strange experiences in order to be complete and sincere. I do not conceal the fact, that it costs me much to relate this, because I do not find herein the conditions of precision, which my experiments in telekinesis, for example, appeared to present. I will add that I do not try to obtain these phenomena of more or less complete materialisations. I suffer them: for the facts do not proceed altogether according to the liking of the experimenter. I cannot say that these apparitions leave me indifferent; on the contrary, they interest me immensely; but I have the impression of being in the presence of a fact, which is too complicated to be usefully observed. It is not the same with raps and telekinesis: and I put forth all my efforts in order to restrict my studies and researches to these phenomena; for I have the feeling that we may be able to arrive at discovering the conditions of their production. I imagine—perhaps wrongly—that, henceforth, we can submit them to scientific discipline; I think that the study of raps and telekinetic phenomena is the necessary preliminary to the study of other, less comprehensible, facts. Therefore, I have devoted myself almost exclusively to their observation; nevertheless, I did not think I was able to dispense with relating everything I had seen. I am entirely ignorant of the signification of these diverse appearances; I may have made a mistake, though I do not think so, but it seems to me I have not the right to make a choice in my experiments, to withhold the one and relate the other. It behoves those who read me to put themselves in the same conditions under which I was placed, and observe in their turn. I confine myself to relating what I have seen. I will add that certain facts have appeared to me more certain than others, but my rôle of witness ends there. The ascertainments I have made in what concerns luminous phenomena, permit me to give some useful indications. The first concern the methods of operation; the others are conclusions which I have drawn from my own experiences. When seeking for simple, luminous phenomena, it is advisable to proceed as I have done for parakinetic and telekinetic phenomena. The sitters group themselves around a table, leaning their hands on it, or form a chain round the table without touching it. Needless to say, the obscurity ought to be as complete as possible. Under these conditions, lights can be obtained; and it is in this way, I observed the woman’s face I have described. The very fine lights which I saw with the young Bordeaux medium (pages 141 and following) were obtained in another manner, which seems to me better still. It is, moreover, the method adopted by professional mediums, perhaps because it favours the execution of fraudulent even more than genuine phenomena. This method consists in placing the medium in the cabinet and forming the chain, either round the table or in a half-circle, in which latter case the chain is not closed.