Drawing is a confirmation of the fact that we represent only a single instant of motion, for a picture can never give us a movement, but only a single state within that movement. At the same time we are content with what the picture renders, even when our image contains only this simple moment of movement. “What is seen or heard, is immediately, in all its definiteness, content of consciousness” (Schuppe)--but its movement is not.
The influence of time upon images is hardly indifferent. We have to distinguish the time necessary for the construction of an image, and the time during which an image lasts with uniform vividness. Maudsley believes the first question difficult to answer. He leans on Darwin, who points out that musicians play as quickly as they can apprehend the notes. The question will affect the lawyer in so far as it is necessary to determine whether, after some time, an image of an event may ensue from which it is possible to infer back to the individuality of the witness. No other example can be used here, because on the rocky problem of the occurrence of images are shattered even the regulative arts of most modern psychophysics.
The second problem is of greater significance. Whether any practical use of its solution can be made, I can not say, but it urges consideration. Exner has observed that the uniform vividness of an image lasts hardly a second. The image as a whole does not disappear in this time, but its content endures unchanged for so long at most. Then it fades in waves. The correctness of this description may be tested by anybody. But I should like to add that my observations of my own images indicate that in the course of a progressive repetition of the recall of an image its content is not equally capable of reproduction. I believe, further, that no essential leaps occur in this alteration of the content of an idea, but that the alteration moves in some definite direction. If, then, I recall the idea of some object successively, I will imagine it not at one time bigger, then smaller, then again bigger, etc.; on the contrary, the series of images will be such that each new image will be either progressively bigger or progressively smaller.