OPTICAL AND MUSCULAR FEELINGS COMBINED.

239

worked up and reproduced in art as well as admired in nature. The finer woods yield it by polish and varnish; a painter's colours are often dull and dead till a transparent film has been superadded. It sometimes redeems the privation of light and colour, as in the jet, or lustrous, black. The green leaf is often adorned by it, through the addition of moisture, if not by an inherent property of the tissue. I am not sure if much of the refreshing influence of greenness in vegetation is not due to lustrous greenness. Animal tissues are the most favourable to this effect. Not only such substances as ivory, bone, and mother of pearl, but silk and wool owe their distinguishing richness and glitter to this cause. It is the chief beauty of the human hair and skin; but the eye is perhaps the finest example that nature affords. In the one case we have an imperfectly transparent film causing a gloss; in the other we have a great depth of perfectly pellucid substance. Through the pupil is seen the jet blackness of the choroid, and the colours of the iris are liquified by the transparency of the aqueous humour.

13. We have next to deal with the complex sensations of sight, those resulting from the combination of optical effect with the feelings of movement arising out of the muscles of the eyeball. As in the case of Touch, this combination is necessary as a basis of those perceptions of the external world that are associated with sight-Externality, Motion, Form, Distance, Expanse, Solidity, and relative Position. It is admitted that mere light and colour will not suffice to found these perceptions upon, and it is my object here, as in the discussions on Muscularity and Touch, to refer them to the moving apparatus of the eye and body generally.

14. I shall commence with motion. One of the earliest acquired of our voluntary actions is the power of following a moving object by the sight. Supposing the eye arrested by a strong light, as a candle flame, the shifting of the candle would draw the eyes after it, partly through their own movements and partly by the rotation of the head. The consequence is a complex sensation of light and movement, just as the sensation of a weight depressing the hand is a sensation of

touch and movement. The movement of the eye now supposed generates an additional pleasure, by superadding the excitement of muscular sensibility to mere optical sensation. It does more; for there is left behind an impression not of light alone, but of light and movement, and if the object comes to be recalled in idea, this is not a mere idea of luminosity restored to the optic nerve, but a joint restoration upon this nerve and the nerves and muscles of the eyeball and head. If the light moves to the right, the right muscles are engaged in following in it; if to the left, the left muscles, and so on; and thus we have several distinct combinations of light and muscular impression marking distinctness of direction, and never confounded with one another. The feeling or sensation caused by movement involves also definite direction according to the muscles engaged, and this compound feeling is the mental or subjective element corresponding to the external fact of a moving object as seen by the eye.

Motion may be not only in any one continuous direction, but may change its direction, and take a course crooked or curved. This brings into play new muscles and combinations, and leaves behind a different trace of muscular action. The right muscles of the eye may have to act along with the superior muscles, and at a shifting rate. This will give an oblique and slanting direction; which we will ever afterwards identify when the same muscles are similarly brought into operation. We have thus a perfect discrimination of varying directions through the distinct muscles that they excite.

Our muscular sensibility also discriminates rate or velocity of movement. A quick movement excites a different feeling from one that is slow; and we thereby acquire graduated sensations, corresponding to degrees of speed, up to a certain limit of nicety.

While the retina of the eye thus receives one and the same optical impression (in the supposed case of the candle flame), this may by movement be imbedded in a great many different muscular impressions, and may constitute a great variety of pictorial effect. By changing the muscles and by varying their rate of action, we may so change the resulting impressions that

SPECTACLE OF MOVING OBJECTS.

241

any one motion shall be recognised by us as distinct from every other, while each may be identified on a recurrence. I do not say that we have yet the perception or notion of a thing external to ourselves, moving through space at a certain speed, because this perception implies a concurrence of senses; such a concurrence of these combined eye-sensations with other senses and movements being, as I believe, the only thing needed to make up the perception as we find it.

Nearly all the pleasures of muscular movement, described in the previous chapter, may be experienced in the spectacle of moving objects. The massive, languid feeling of slow movement, the excitement of a rapid pace, the still higher pleasure of a waxing or waning speed, can all be realized through the muscles of the eye and the head. The slow procession, the gallop of a race-horse, the flight of a cannon-ball, exhibit different varieties of the excitement of motion. In the motion of a projectile, where a rapid horizontal sweep is accompanied with a gentle rise and fall, we have one set of muscles in quick tension and another set in slow tension, making a mixed and more agreeable effect. Motions in curves are the best means of giving this pleasing combination, and also the still more pleasing effect of increasing and dying motion. When a projectile flies across the field of view the horizontal motion is uniform, but the pace upwards diminishes, and at last dies away at the highest point; the body then recommences a downward course, slow at first, but accelerating until it reach the ground. Whatever gratification there may be in the increase and diminution of movement is obtained through the muscles concerned in raising and lowering the eyes, while the muscles that give a horizontal movement would not be similarly gratified unless by an effect of perspective in an oblique view.

The pleasures of moving objects and stirring spectacle count for much in the excitement of human life. They are really pleasures of action; but inasmuch as only a very limited portion of muscle is excited by them, they do not constitute bodily exercise, and are therefore to all practical intents passive pleasures, like music or sunshine. Thus dramatic spectacle,

R

the ballet, the circus, the horse race, the view of parties engaged in sports—although engaging the activity of the eye, do not belong properly to active enjoyments.

15. Among the permanent imagery of the intellect, recalled, combined, and dwelt upon in many ways, we are to include visible movements. The flight of a bird is a characteristic that distinguishes one species from another, and the impression left by it is part of our knowledge or recollection of each individual kind. The gallop of a horse is a series of moving pictures that leave a trace behind them, and are revived as such. The motions that constitute the carriage and expression of an animal or a man, demand particular movements of the eye in order to take them in, and store them up among our permanent notions. All the gestures, modes of action, and changes of feature that emotion inspires are visible to the eye as an assemblage of movements, and we recognise such movements as marking agreement or difference among individuals and between different passions. Many of the aspects of the external world impress themselves upon the moving apparatus of the eye. The waves of the sea, the drifting of clouds, the fall of rain, the waving of the trees under the wind, the rushing of water, the darting of meteors, the rising and setting of the sun, are all mixed impressions of spectacle and movement. In like manner, in the various processes of the arts, there are characteristic movements to constitute our notions and means of discrimination of those processes. The evolutions of armies have to be remembered as movements, and therefore need to be embodied among the muscular recollections of the system.

16. We ought next to consider the sensations of Form, or of the outlines of objects at rest. For this purpose it is advisable to allude first to the sensations of distance from the eye, these being in fact included in the imagery of movement just discussed. We have already seen that there is a double adaptation of the eye to distance, namely, a change in the ball, for near distances, and an alteration in the direction of the two eyes, or in the parallelism of the axes, for all distances near and far. These adaptations are undoubtedly muscular;

SENSATION OF DISTANCE.

243

that is, they consist in the greater or less contraction of particular muscles. Now, the contraction of muscles in any part whatever yields a distinct feeling; we are conscious not only of the fact of tension, but of different degrees of tension. Hence every change in the interior of the ball by muscular influence, and in the convergence of the axes, causes a change of feeling; we have a discriminative consciousness of all the different stages of adaptation. The consciousness of sight at six inches is never confounded with the consciousness of a foot, and this last is widely different from the feeling of a hundred feet. Thus it is that our minds are differently affected by different distances, so that we cannot confound an object at five feet with an object at fifty feet. The discrimination is of the same nature, although not so nice, as in drawing the hand across a table from an object thirty inches off to another object close at our side. The difference of muscular tension is unmistakeable.

In this way, therefore, the eye gives us a means of distinguishing objects, according as they are far or near, through the feelings consequent on the muscular adaptation for securing distinctness of vision. An object moving away from the eye in a straight line would give us a changing sensation no less than an object moving across the field of view. object moving obliquely, that is receding or approaching, while going across the view, would give a complex feeling embodied in the movements of the eye and head, and in the movements of adaptation.

An

There is a distinct emotional sensibility in the feeling of distance, more especially of remote distance. A far object. exalts the muscular feeling of the eye, and is a source of lively pleasure the pleasure of muscular tension in muscles peculiarly sensitive. The principal effort for a distant view is concentrated in the two adductor muscles of the two eyes, which have distinct nerves supplied to them. By these, the axes of the eye are drawn from a converging to a parallel position. This exercise of the adductor muscles is part of the pleasure derived from the outside prospect after in-door confinement. 17. We may pass now to the consideration of form, shape,