SECTION XVI.
WHY DARKNESS IS TERRIBLE.
It may be worth while to examine how darkness can operate in such a manner as to cause pain. It is observable, that still as we recede from the light, nature has so contrived it, that the pupil is enlarged by the retiring of the iris, in proportion to our recess. Now, instead of declining from it but a little, suppose
that we withdraw entirely from the light; it is reasonable to think that the contraction of the radial fibres of the iris is proportionally greater; and that this part may by great darkness come to be so contracted, as to strain the nerves that compose it beyond their natural tone; and by this means to produce a painful sensation. Such a tension it seems there certainly is, whilst we are involved in darkness; for in such a state, whilst the eye remains open, there is a continual nisus to receive light; this is manifest from the flashes and luminous appearances which often seem in these circumstances to play before it; and which can be nothing but the effect of spasms, produced by its own efforts in pursuit of its object: several other strong impulses will produce the idea of light in the eye, besides the substance of light itself, as we experience on many occasions. Some, who allow darkness to be a cause of the sublime, would infer, from the dilatation of the pupil, that a relaxation may be productive of the sublime as well as a convulsion: but they do not, I believe, consider, that although the circular ring of the iris be in some sense a sphincter, which may possibly be dilated by a simple relaxation, yet in one respect it differs from most of the other sphincters of the body, that it is furnished with antagonist muscles, which are the radial fibres of the iris: no sooner does the circular muscle begin to relax, than these fibres, wanting their counterpoise, are forcibly drawn back, and open the pupil to a considerable wideness. But though we were not apprised of this, I believe any one will find, if he opens his eyes and makes an effort to see in a dark place, that a very perceivable pain ensues. And I have heard some ladies remark, that after hav
ing worked a long time upon a ground of black, their eyes were so pained and weakened, they could hardly see. It may perhaps be objected to this theory of the mechanical effect of darkness, that the ill effects of darkness or blackness seem rather mental than corporeal: and I own it is true that they do so; and so do all those that depend on the affections of the finer parts of our system. The ill effects of bad weather appear often no otherwise than in a melancholy and dejection of spirits; though without doubt, in this case, the bodily organs suffer first, and the mind through these organs.
SECTION XVII.
THE EFFECTS OF BLACKNESS.
Blackness is but a partial darkness; and therefore it derives some of its powers from being mixed and surrounded with colored bodies. In its own nature, it cannot be considered as a color. Black bodies, reflecting none, or but a few rays, with regard to sight, are but as so many vacant spaces, dispersed among the objects we view. When the eye lights on one of these vacuities, after having been kept in some degree of tension by the play of the adjacent colors upon it, it suddenly falls into a relaxation; out of which it as suddenly recovers by a convulsive spring. To illustrate this: let us consider that when we intend to sit on a chair, and find it much lower than was expected, the shock is very violent; much more violent than could be thought from so slight a fall as the difference between one chair and another can possibly make. If, after descending a flight of stairs, we attempt inad
vertently to take another step in the manner of the former ones, the shock is extremely rude and disagreeable: and by no art can we cause such a shock by the same means when we expect and prepare for it. When I say that this is owing to having the change made contrary to expectation; I do not mean solely, when the mind expects. I mean likewise, that when any organ of sense is for some time affected in some one manner, if it be suddenly affected otherwise, there ensues a convulsive motion; such a convulsion as is caused when anything happens against the expectance of the mind. And though it may appear strange that such a change as produces a relaxation should immediately produce a sudden convulsion; it is yet most certainly so, and so in all the senses. Every one knows that sleep is a relaxation; and that silence, where nothing keeps the organs of hearing in action, is in general fittest to bring on this relaxation; yet when a sort of murmuring sounds dispose a man to sleep, let these sounds cease suddenly, and the person immediately awakes; that is, the parts are braced up suddenly, and he awakes. This I have often experienced myself, and I have heard the same from observing persons. In like manner, if a person in broad daylight were falling asleep, to introduce a sudden darkness would prevent his sleep for that time, though silence and darkness in themselves, and not suddenly introduced, are very favorable to it. This I knew only by conjecture on the analogy of the senses when I first digested these observations; but I have since experienced it. And I have often experienced, and so have a thousand others, that on the first inclining towards sleep, we have been suddenly awakened with a most violent start; and that this start was gener
ally preceded by a sort of dream of our falling down a precipice: whence does this strange motion arise, but from the too sudden relaxation of the body, which by some mechanism in nature restores itself by as quick and vigorous an exertion of the contracting power of the muscles? The dream itself is caused by this relaxation; and it is of too uniform a nature to be attributed to any other cause. The parts relax too suddenly, which is in the nature of falling; and this accident of the body induces this image in the mind. When we are in a confirmed state of health and vigor, as all changes are then less sudden, and less on the extreme, we can seldom complain of this disagreeable sensation.
SECTION XVIII.
THE EFFECTS OF BLACKNESS MODERATED.
Though the effects of black be painful originally, we must not think they always continue so. Custom reconciles us to everything. After we have been used to the sight of black objects, the terror abates, and the smoothness and glossiness, or some agreeable accident of bodies so colored, softens in some measure the horror and sternness of their original nature; yet the nature of the original impression still continues. Black will always have something melancholy in it, because the sensory will always find the change to it from other colors too violent; or if it occupy the whole compass of the sight, it will then be darkness; and what was said of darkness will be applicable here. I do not purpose to go into all that might be said to illustrate this theory of the effects of light and