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refraction, but, likewise, upon the degree of force with which it acts; and this, as well as the quantity, depends, in a great measure, upon the degrees of proximity between the object and the organ. Hence in proportion as bodies are near, their outlines appear more sharp, their colours more vivid, and their lights and shadows more forcible and distinct; and, in proportion as they recede from us, all these gradually fade away, till at length they entirely vanish. Hence there are visible variations in the eye according to the distance of the object, to which it is directed; which seem to be produced by the greater or smaller degrees of irritation caused by impressions more or less vivid*.

* It has been calculated that objects are visible at the distance of 3436 times their diamee, if viewed by eyes perfectly organized, and through the common medium of common daylight equally diffused from the organ to the object but in proportion as the comparative degree of light is greater upon the object than upon the eye, this power of seeing it at a distance will be extended; and in proportion as it is less, it will be shortened. We can see a burning coal by night at least 100 times as far as we can see the same coal extinct by daylight; and the difference is proportionately great between looking out of an obscure room upon objects in sunshine, and looking from sunshine at objects in an obscure room.

The above calculation relates of course to the powers of the human eye; there being many kinds of birds of prey, such as eagles, kites, &c. which manifestly possess them in a much greater extent.

CHAP.
V.

Of Sight.

CHAP.

V.

Of Sight.

29. Similar variations are produced, as before observed, by different quantities of light thrown directly upon the eyes; the membrane of the iris contracting with its increase, and dilating with its decrease, in proportion as the irritation is more or less violent. When extended beyond a certain degree, it becomes absolutely painful; and in that case, the eloquent author, already so often cited, by mistaking as usual a power for a sensation, concludes it to be sublime*; though if he or any other person had been compelled to expose their eyes to unsufferable light for a few moments, they would have felt how totally void of all sublime ideas their minds would have become, how much soever the power and magnificence of such light, surrounding the throne of Omnipotence, might have exalted or expanded their imaginations, when described in the verses of Milton.

30. Darkness is the entire cessation or absence of light; and, of course, utterly negative, and producing no sensation at all of itself: but, nevertheless, when we go suddenly out of a very strong light into it, the transition, like all other very violent and quick transitions, may be painful to very tender eyes; as there will ensue a sudden change in the internal state of the fibres; which, notwithstanding

* Sublime and Beautiful, Part II. f. xiv. et seq.

that it be from tension to relaxation, and from irritation to repose, may nevertheless, in the first sensation of it, be unpleasant to some organs, though I could never feel it so. But to imagine that darkness is painful to the sight, because we sometimes strain our eyelids to such a degree as to produce pain, in the efforts which we make to see in the dark*, is one of the most unaccountable fancies that ever arose in the mind of any man: for if darkness be in itself painful, a person with his eyes shut in a dark room must be in an agony; and yet so widely does the practice of mankind differ from the theories of philosophers, that this is the state, in which we all usually go to sleep; and is probably that, in which this great philosopher and statesman slept as well as the meanest of the swinish multitude. It is to darkness, likewise, that men fly for relief, when their eyes, through weakness or inflammation, cannot bear the irritation of light: but I never yet heard of any one, whose eyes were so heterogeneously organized, or so strangely morbid, that they could not bear the effect of darkness, whatever it may be for as to the uneasiness, which the boy, couched by Cheselden, felt at the first sight of a black object, it arose either from the harshness of its outline, or from its appearing

Part IV. f. xv. &c.

CHAP.

V.

Of Sight.

CHAP.

V.

Of Sight.

to act as a partial extinguisher applied to his eyes; which, as every object, that he saw, seemed to touch them, would, of course, be its effect. It could not possibly have been, as the author supposes, on account of his finding darkness painful; as it was not till long after the operation that he could bear to have his eyes exposed to the light, or endure any thing but darkness for any considerable time together. All very sharp, broken, or angular objects were disagreeable to him, as they are to all eyes of very nice sensibility.

31. But it will be said, perhaps, that the painful sensations, of which this author speaks, are no common pains; but such as render the sensations, to which they belong, sublime, and therefore only capable of being felt by minds capable of exaltation to sublimity, Such his unquestionably was, in the highest degree; and if ever man had a just claim to the privilege of being visited by sublime visions, whether sleeping or waking, he was undoubtedly the man: but, if we admit this privation to be a source of the sublime, I do not know how we shall be able to exclude silence, which is a privation of sound, as darkness is of light; and, for its being sublime upon his own principles, we have the high authority of Virgil-" simul ipsa silentia terrent:" but, nevertheless, even his ingenuity would have found some difficulty in proving

silence a sensation; though he certainly felt it painful on many occasions. There are other privations, however, which it is surprising that he has omitted; since they make themselves most sensibly, and in some instances, most painfully felt throughout all the animal creation; and when personified as powers, and described in poetry, are as truly sublime, as any of the other powers, which he mistook for sensations.

Close by the regal chair,

Fell Thirst and Famine scowl

A baleful smile upon their 'baffled guest. Yet no one, I believe, ever found either hunger or thirst to be a sublime sensation; or found his mind elevated or expanded by suffering them. On the contrary, they have been generally esteemed to be most debasing and humiliating to the pride of human nature; as they not only level the highest with the lowest -the prince with the beggar, and the philosopher with the idiot, but man with the brute.

32. The example of this great author proves how difficult it is to keep the operations of the different faculties of the mind distinct from each other; so as to consider sensation singly and alone, unmixed with, and uninfluenced by the ideas previously imprinted in the memory, or the deductions made from them by the understanding; both of which have become, in

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