Dr. Macgregor's remarks on the involuntary and unwelcome nature of the
visions is borne out by what Scheffer, as already quoted, says concerning
the Lapps.

In addition to visions which thus come unsought, contributing knowledge of
things remote or even future, we may glance at visions which are provoked
by various methods. Drugs (_impepo_) are used, seers whirl in a wild
dance till they fall senseless, or trance is induced by various kinds of
self-suggestion or 'auto-hypnotism.' Fasting is also practised. In modern
life the self-induced trance is common among 'mediums'--a subject to which
we recur later.

So far, it will be observed, our evidence proves that precisely similar
_beliefs_ as to man's occasional power of opening the gates of distance
have been entertained in a great variety of lands and ages, and by races
in every condition of culture.[23] The alleged experiences are still
said to occur, and have been investigated by physiologists of the eminence
of M. Richet. The question cannot but arise as to the residuum of fact in
these narrations, and it keeps on arising.

In the following chapter we discuss a mode of inducing hallucinations
which has for anthropologists the interest of universal diffusion. The
width of its range in savage races has not, we believe, been previously
observed. We then add facts of modern experience, about the authenticity
of which we, personally, entertain no doubt; and the provisional
conclusion appears to be that savages have observed a psychological
circumstance which has been ignored by professed psychologists, and which,
certainly, does not fit into the ordinary materialistic hypothesis.