Let us now contrast with this what happens when you sit still with your eyes shut, calling up pictures of places you have seen abroad, and perhaps ultimately falling asleep. Dr. Watson, if I understand him aright, maintains that either there is actual stimulation of the retina, or your pictures are mere word-pictures, the words being represented by small actual movements such as would, if magnified and prolonged, lead to actual pronunciation of the words. Now if you are in the dark with your eyes shut, there is no stimulation of the retina from without. It may be that, by association, the eye can be affected through stimuli to other senses; we have already had an example in the fact that the pupil can be taught to contract at a loud noise if this had been frequently experienced along with a bright light. We cannot, therefore, dismiss the idea that a stimulus to one sense may, as a result of past events, have an effect upon the organs of another sense. “Images” might be definable as effects produced in this way. It may be that, when you see a picture of Napoleon, there is an effect upon your aural nerves analogous to that of having the word “Napoleon” pronounced in your presence, and that that is why, when you see the picture, the word “Napoleon” comes into your head. And similarly, when you shut your eyes and call up pictures of foreign scenes, you may actually pronounce, completely or incipiently, the word “Italy”, and this may, through association, stimulate the optic nerve in a way more or less similar to that in which some actual place in Italy stimulated it on some former occasion. Thence association alone may carry you along through a series of journeys, until at last, when you fall asleep, you think you are actually making them at the moment. All this is quite possible, but so far as I know there is no reason to hold that it is more than possible, apart from an _a priori_ theory excluding every other explanation.