Page:Mind (New Series) Volume 8.djvu/104

 90 CKITICAL NOTICES : This brings me to my real difficulty. One would like to b& convinced by so comprehensive a theory. The principles employed are undoubted the law of the unconscious working of mind as Dr. Lipps understands the phrase the question of the propriety of names not being raised ; and again, the method of reading our own personality into objects. But what I miss is a point of application for these ideas of forces. If I treat an object as one, it is because the object gives me many and coherent presentations in a combination familiar to me from my experience of myself. Before we can apply the idea of force we must feel or imagine the figures to be the seat of movements, there must be something in our experience of the figure which either is or suggests an ex- perience of movement. But where this exists, what need to seek a further cause (I mean a further consciously entertained cause) of the illusion ? More movement in a certain direction means more extension in that direction. If the legs of the Muller-Lyer figure draw my eyes on really (as seems to me to be often the case) or in idea, the illusion may in these cases be at once ex- plained. It is well known that optical illusions are referred by Prof. Wundt to actual or anticipated eye -movements, and he has recently restated his view (with additional matter which does not directly concern us here) in an important treatise Die Geometnsch-optische Tduschungen, Leipzig, 1898 (repeated in substance in Phil. Stud, xiv., Heft 1). In some of the cases he adduces my own feelings of movement in the eyes are so marked that I find an explanation by reference to the kinsesthetic experi- ences of the eyes to be the most natural in the world. Dr. Lipps will have nothing to do with eye-movements as an integral factor in space-perception. Now, one may confess that no extant theory of them is satisfactory, and that much which used to be explained by them may be plausibly explained without them. Still one may point to exploration and fail to understand the impertinent super- fluity of the experience of eye-movement if it is only the mere physical movement which is of use. And again one may urge that these very optical illusions are an important chapter in the theory of space-perception, and demand discussion on their own merits. Consequently I, and perhaps others, feel that it is wiser to be off with the old love before we are on with the new. Hence the difficulty which I should like to have removed before accepting Dr. Lipps' theory of mechanical interpretation as explaining all geometrical illusions, is that in the present state- ment his forces seem stuck on to given data, and not an outgrowth from them, and that when their connexion is realised through the implication of movement they are, at least in some cases,. superfluous for the primary purpose. But this would only pre- vent us from identifying the cause of optical illusions and of the aesthetic effect of the figures. For this interpretation may be the analysis of the forces at work in the movements contained or im- plied in the perception of the figures, and as such would be of the.