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.
This variety of illusion is illustrated in the case in which a present feeling or thought is confounded with some inference based on it.

For example, a present thought may, through forgetfulness, be regarded as a new discovery.

Its originality appears to be immediately made known in the very freshness which characterizes it.

Every author probably has undergone the experience of finding that ideas which started up to his mind as fresh creations, were unconscious reminiscences of his own or of somebody else's ideas.
In the case of present emotional states this liability to confuse the present and the past is far greater.

Here there is something hardly distinguishable from an active illusion of sense-perception.