"Now that the mental functions are known to be inseparably connected with nervous substrata, disposed and united in the brain in the most orderly fashion, superordinate, co-ordinate, and subordinate--the whole a complex organisation of confederate nerve centres, each capable of more or less independent action--a natural interpretation presents itself. The extraordinary states of mental disintegration evince the separate and irregular function of certain mental nerve tracts, or grouped nerve tracts with which goes necessarily a coincident suspension, partial or complete, of the functions of all the rest; the supernatural incubus, therefore, neither demoniac nor divine, only morbid. Thus the strange nervous seizures, with their mental concomitants, not being outside the range of positive research, but interesting events within it, become useful natural experiments to throw an instructive light upon the intricate functions of the most complex organ in the world--the human brain. Steadily are the researches of pathology driving the supernatural back into its last and most obscure retreat; for they prove that in the extremest ecstasies there is neither _theolepsy_ nor _diabolepsy_, nor any other _lepsy_ in the sense of possession of the individual by an external power; what there is truly is a _psycholepsy_."[34] States of exaltation produced by the aid of drugs, fasting, or other forms of self-torture come naturally under the category of deliberately induced states of mind, owing to the conviction that spiritual knowledge may be gained in this way. But there are other states that arise naturally and which foster the same conviction. It has already been pointed out that the generally accepted theory with uncivilised peoples is that all disease is due to the action of malevolent spirits. There is no need now to repeat proof of this, and in any case it lies to hand in any work that deals with uncivilised life. Nor need we go back to uncivilised times for evidence. One requires only to look but a very little way into the history of any country to find the supernaturalistic theory of disease in full swing, and even to-day one may discover indications of its once general rule. Its importance to the present enquiry lies in the part it has played in building up in the religious consciousness a general conviction of religious truth that does not disappear even when it is seen that the evidence upon which it rests is faulty. Just as the inhabitants of a Welsh village have their general belief in religion strengthened by the semi-hysterical speeches of an Evan Roberts, and the convulsive capers of a whole congregation, so in all ages people have found endorsement of their belief in a supernatural world in the existence of cases the pathological nature of which admits of no doubt. Belief in the supernatural character of specific nervous conditions or mental states may disappear, but the fact that this