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
belief has been general for a time leaves behind a certain psychological
residuum in favour of supernaturalism in general.

The connection between the