If we look closely into this variety of illusion, we shall see that it is very similar in its structure and origin to that kind of erroneous perception which arises from inattention to the actual impression of the moment under the influence of a strong expectation of something different.  The representation of ourselves as entertained dislodges from our internal field of vision our actual condition, relegating this to the region of obscure consciousness.  Could we for a moment get rid of this representation and look at the real feelings of the time, we should become aware of our error; and it is possible that the process of becoming blase involves a waking up to a good deal of illusion of the kind.

Just as we can thus deceive ourselves within certain limits as to our emotional condition, so we can mistake the real nature of our intellectual condition.  Thus, when an idea is particularly grateful to our minds, we may easily imagine that we believe it, when in point of fact all the time there is a sub-conscious process of criticism going on, which if we attended to it for a moment would amount to a distinct act of disbelief.  Some persons appear to be capable of going on habitually practising this petty deceit on themselves, that is to say, imagining they believe what in fact they are strongly inclined to doubt.  Indeed, this remark applies to all the grateful illusions respecting ourselves and others, which will have to be discussed by-and-by.  The impulse to hold to the illusion in spite of critical reflection, involves the further introspective illusion of taking a state of doubt for one of assurance.  Thus, the weak, flattered man or woman manages to keep up a sort of fictitious belief in the truth of the words which are so pleasant to the ear.

It is plain that the external conditions of life impose on the individual certain habits of feeling which often conflict with his personal propensities.  As a member of society he has a powerful motive to attribute certain feelings to himself, and this motive acts as a bias in disturbing his vision of what is actually in his mind.  While this holds good of lighter matters, as that of enjoyment just referred to, it applies still more to graver matters.  Thus, for example, a man may easily persuade himself that he feels a proper sentiment of indignation against a perpetrator of some mean or cruel act, when as a matter of fact his feeling is much more one of compassion for the previously liked offender.  In this way we impose on ourselves, disguising our real sentiments by a thin veil of make-believe.

So far I have spoken of an illusion of introspection as analogous to the slight misapprehensions of sense-impression which were touched on in connection with illusions of sense (Chapter III.).  It is to be observed, however, that the confusing of elements of consciousness, which is so prominent a factor in introspective illusion, involves a species of error closely analogous to a complete illusion of perception, that is to say, one which involves a misinterpretation of a sense-impression.