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.