o discern is the class of
facts that have kept the religious idea alive.

The foregoing pages constitute an attempt to answer this question. The
need for some such investigation was clearly shown by the publication of
the late Professor William James's _Varieties of Religious Experience_
and its reception by the religious press of the country as an
epoch-marking work. As a mere collection of documents, the work is
interesting enough. But its critical value is extremely small. How
religious visionaries have felt, or what has been their experiences, can
only furnish the mere data of an enquiry, and _their explanation of the
cause of their experiences is a part of the data_. This, apparently,
Professor James overlooked; and it will be noted by critical readers of
his book that it proceeds on the assumption that the statements of
religious visionaries are to be taken, not only as true concerning their
subjective experiences at a given time, but also as approximately true
as to the causes of their mental states. This, of course, by no means
follows. A scientific enquiry cannot separate mental conditions from the
subject's interpretation of their causation. Whether this interpretation
is genuine or not must be decided finally by an appeal to what is known
of the laws of mental life, under both normal and abnormal conditions.
If these are adequate to explain the "Varieties of Religious
Experience," there is no need whatever to assume the operation of a
supernatural agency. Nor does calling this agency 'transcendent' or
'supermundane' make any substantial difference. For, in this connection,
these are only names that serve to disguise a visitant of a highly
undesirable character.

The evidence on behalf of a naturalistic explanation of religious
phenomena has been purposely stated in a suggestive rather than in an
exhaustive manner. The main lines of evidence are threefold. First,
there is the indisputable fact that in the lower stages of culture all
mental and bodily diseases are universally attributed to spiritual
agency. This explanation holds the field; it is the only one possible at
the time, and it is not replaced until a comparatively late stage of
human history. But of special importance is the fact that a belief does
not die out suddenly. It is only destroyed very slowly, and even after
the facts upon which the belief was originally based have been otherwise
interpreted, the attitude of mind engendered by the long rei