Very often the personification complains of too much light, and during several sittings insists upon darkness. We must politely resist it, and make it understand that psychical phenomena lose much of their value, as soon as they cease to be visible. I never hesitate telling the personification, that experiments of this kind are not convincing when conducted in obscurity, since the good faith of the operators is then open to suspicion, and, moreover, that phenomena can be obtained in full light. These reasons often prevail on the personification not to persist in asking for darkness. In some cases, it is the personification itself who refuses to operate in darkness. It is with personifications of this class that I have obtained the finest results. When the pseudo-entity asks one or other of the experimenters to leave the circle, it is prudent to yield obedience to its behest, unless, for various reasons, the required elimination be unacceptable. In that case, it is as well to explain these reasons to the personification, and then it rarely happens they are not accepted. Such are the general rules which a fairly long experience has caused me to adopt, and I have always had reason to be glad of having followed them. In experiments conducted by me, I have never received obscene or absurd communications of which certain people complain. Reflecting, perhaps, my own state of mind, I have generally encountered personifications with scientific and serious tendencies. I have just exposed in detail, and perhaps too minutely, the conclusions arrived at concerning the method of operation. I now come to the indication of the results which I have obtained, and the ascertainments I have been able to make. I will examine in succession raps, movements without contact, luminous phenomena, and finally, intellectual phenomena. CHAPTER II RAPS I will not stop to consider movements with contact. From a physical point of view they have no serious signification whatever. They are so easily explained by the combined, unconscious, muscular movements of the experimenters, that it is really not worth while stopping to examine them. The messages obtained by their intermedium may present an internal or clinical interest, but in that case they belong to the category of intellectual phenomena, properly so-called. The first physical phenomena, which deserves attention, is that of ‘raps.’ It is generally the one most frequently obtained. We must, however, point out that the faculties of mediums are not identical: some produce chiefly physical, others chiefly intellectual phenomena. The former also manifest diverse qualities: some of them obtain raps, others movements, others luminous phenomena. Still in a general way ‘raps’ have seemed to me to be one of the simplest phenomena of a material order.