es, hardly distinguishable from the admittedly insane. And this
way of thinking of illusion and its subjects is strengthened by one of
the characteristic sentiments of our age. The nineteenth century
intelligence plumes itself on having got at the bottom of mediaeval
visions and church miracles, and it is wont to commiserate the feeble
minds that are still subject to these self-deceptions.

According to this view, illusion is something essentially abnormal and
allied to insanity. And it would seem to follow that its nature and
origin can be best studied by those whose speciality it is to observe
the phenomena of abnormal life. Scientific procedure has in the main
conformed to this distinction of common sense. The phenomena of illusion
have ordinarily been investigated by alienists, that is to say,
physicians who are brought face to face with their most striking forms
in the mentally deranged.

While there are very good reasons for this treatment of illusion as a
branch of mental pathology, it is by no means certain that it can be a
complete and exhaustive one. Notwithstanding the flattering supposition
of common sense, that illusion is essentially an incident in abnormal
life, the careful observer knows well enough that the case is far
otherwise.

There is, indeed, a view of our race diametrically opposed to the
flattering opinion referred to above, namely, the humiliating judgment
that all men habitually err, or that illusion is to be regarded as the
natural condition of mortals. This idea has found expression, not only
in the cynical exclamation of the misanthropist that most men are fools,
but also in the cry of despair that sometimes breaks from the weary
searcher after absolute truth, and from the poet when impressed with the
unreality of his early ideals.

Without adopting this very disparaging opinion of the intellectual
condition of mankind, we must recognize the fact that most men are
sometimes liable to illusion. Hardly anybody is always consistently
sober and rational in his perceptions and beliefs. A momentary fatigue
of the nerves, a little mental excitement, a relaxation of the effort of
attention by which we continually take our bearings with respect to the
real world about us, will produce just the same kind of confusion of
reality and phantasm, which we observe in the insane. To give but an
example: the play of fancy which leads to a detection of animal and
other forms in clouds, is known to be an o