In certain morbid conditions of mind, and in the case of the few healthy minds endowed with special imaginative force, the products of this mental activity, may, as we saw when dealing with illusions of perception, closely resemble dreams in their vividness and apparent actuality.

When this is the case, illusions of memory may arise at once just as in the case of dreams.

This will happen more easily when the imagination has for some time been occupied with the same group of ideal scenes, persons, or events.

To Dickens, as is well known, his fictitious characters were for the time realities, and after he had finished his story their forms and their doings lingered with him, assuming the aspect of personal recollections.

So, too, the energetic activity of imagination which accompanies a deep and absorbing sympathy with another's painful experiences, may easily result in so vivid a realization of all their details as to leave an after-sense of _personal_ suffering.