er of the feeling
does not change, its intensity is undergoing alterations so that an
accurate observation of its quantity is impracticable. Also, in this
unstable shifting internal scene features may appear for a duration too
short to allow of close recognition. In this way it happens that we
cannot sharply divide the feeling of the moment from its antecedents and
its consequents.

If, now, we take these facts in connection with what has been said above
respecting the nature of the process of introspection, the probability
of error will be made sufficiently clear. To transfix any particular
feeling of the moment, to selectively attend to it, and to bring it
under the proper representation, is an operation that requires time, a
time which, though short, is longer than the fugitive character of so
much of our internal mental life allows. From all of which it would
appear to follow that it must be very easy to overlook, confuse, and
transform, both as to quality and as to quantity, the actual ingredients
of our internal consciousness.

From these sources there spring a number of small errors of
introspection which, to distinguish them from others to be spoken of
presently, may be called passive. These would include all errors in
detecting what is in consciousness due to the intricacies of the
phenomena, and not aided by any strong basis. For example, a mental
state may fail to disclose its component parts to introspective
attention. Thus, a motive may enter into our action which is so
entangled with other feelings as to escape our notice. The fainter the
feeling the greater the difficulty of detaching it and inspecting it in
isolation. Again, an error of introspection may have its ground in the
fugitive character of a feeling. If, for example, a man is asked whether
a rapid action was a voluntary one, he may in retrospection easily
imagine that it was not so, when as a matter of fact the action was
preceded by a momentary volition. When a person exclaims, "I did a thing
inadvertently or mechanically," it often means that he did not note the
motive underlying the action. Such transitory feelings which cannot at
the moment be seized by an act of attention are pretty certain to
disappear at once, leaving not even a temporary trace in consciousness.

We will now pass to the consideration of other illusions of
introspection more analogous to what I have called the active illusions
of perception. In our examination of these