The Sense of Beauty: Being the Outlines of Aesthetic Theory

by George Santayana

Physiology of the perception of form.

§ 20. The charm of a line evidently consists in the relation of its parts; in order to understand this interest in spatial relations, we must inquire how they are perceived.[4] If the eye had its sensitive surface, the retina, exposed directly to the light, we could never have a perception of form any more than in the nose or ear, which also perceive the object through media. When the perception is not through a medium, but direct, as in the case of the skin, we might get a notion of form, because each point of the object would excite a single point in the skin, and as the sensations in different parts of the skin differ in quality, a manifold of sense, in which discrimination of parts would be involved, could be presented to the mind. But when the perception is through a medium, a difficulty arises.

Any point, α, in the object will send a ray to every point, a', b', c', of the sensitive surface; every point of the retina will therefore be similarly affected, since each will receive rays from every part of the object.

If all the rays from one point of the object, a, are to be concentrated on a corresponding point of the retina, α, which would then become the exclusive representative of α, we must have one or more refracting surfaces interposed, to gather the rays together. The presence of the lens, with its various coatings, has made representation of point by point possible for the eye. The absence of such an instrument makes the same sort of representation impossible to other senses, such as the nose, which does not smell in one place the effluvia of one part of the environment and in another place the effluvia of another, but smells indiscriminately the combination of all. Eyes without lenses like those possessed by some animals, undoubtedly give only a consciousness of diffused light, without the possibility of boundaries or divisions in the field of view. The abstraction of colour from form is therefore by no means an artificial one, since, by a simplification of the organ of sense, one may be perceived without the other.

But even if the lens enables the eye to receive a distributed image of the object, the manifold which consciousness would perceive would not be necessarily a manifold of parts juxtaposed in space. Bach point of the retina might send to the brain a detached impression; these might be comparable, but not necessarily in their spatial position. The ear sends to the brain such a manifold of impressions (since the ear also has an apparatus by which various external differences in rapidity of vibrations are distributed into different parts of the organ). But this discriminated manifold is a manifold of pitches, not of positions. How does it happen that the manifold conveyed by the optic nerve appears in consciousness as spatial, and that the relation between its elements is seen as a relation of position?

An answer to this question has been suggested by various psychologists. The eye, by an instinctive movement, turns so as to bring every impression upon that point of the retina, near its centre, which has the acutest sensibility. A series of muscular sensations therefore always follows upon the conspicuous excitement of any outlying point. The object, as the eye brings it to the centre of vision, excites a series of points upon the retina; and the local sign, or peculiar quality of sensation, proper to each of these spots, is associated with that series of muscular feelings involved in turning the eyes. These feelings henceforth revive together; it is enough that a point in the periphery of the retina should receive a ray, for the mind to feel, together with that impression, the suggestion of a motion, and of the line of points that lies between the excited point and the centre of vision. A network of associations is thus formed, whereby the sensation of each retinal point is connected with all the others in a manner which is that of points in a plane. Every visible point becomes thus a point in a field, and has a felt radiation of lines of possible motion about it. Our notion of visual space has this origin, since the manifold of retinal impressions is distributed in a manner which serves as the type and exemplar of what we mean by a surface.

Values of geometrical figures.

§ 21. The reader will perhaps pardon these details and the strain they put on his attention, when he perceives how much they help us to understand the value of forms. The sense, then, of the position of any point consists in the tensions in the eye, that not only tends to bring that point to the centre of vision, but feels the suggestion of all the other points which are related to the given one in the web of visual experience. The definition of space as the possibility of motion is therefore an accurate and significant one, since the most direct and native perception of space we can have is the awakening of many tendencies to move our organs.