If indeed, the necessary supply were long neglected, the morbid state of the body which would ensue, though no pain of actual hunger were to be felt, would convince, at last, the sufferer of his folly. But the providence of our gracious Creator, has not trusted the existence of man to the dangerous admonition of so rough a monitor, which might, perhaps, bring his folly before him only when it was too late to be wise. The pain of hunger--that short disease, if it may be so termed, which it is in our power so speedily to cure, prevents diseases that more truly deserve the name. Between _satiety_ on one side, and _want_ on the other, the stream of health flows tranquilly along, which, but for these boundaries, would speedily waste itself and disappear; as the most magnificent river, which, if dispersed over a boundless plain, would flow almost into nothing, owes its abundance and majestic beauty to the very _banks_ that seem to confine its waters within too narrow a channel. Besides those particular feelings of bodily uneasiness, which, as attended with desire, constitute our appetites, there are other affections of the same class, which, though not usually ranked with our external sensations or perceptions, because we find it difficult to ascribe them to any local organ, are unquestionably to be arranged under the same head; since they are feelings which arise, as immediately and directly from a certain state of a part of the nervous system, as any of the feelings which we more commonly ascribe to external sense. Of this kind is that muscular pleasure of _alacrity_ and action, which forms so great a part of the delight of the _young_ of every species of living beings, and which is felt, though in a less degree, at every period of life, even the most advanced; or which, when it ceases in age, only gives place to another species of muscular pleasure--that which constitutes the pleasure of ease--the same species of feeling, which doubles, to ever one, the delight of exercise, by sweetening the repose to which it leads, and thus making it indirectly, as well as directly, a source of enjoyment. In treating of what have been termed the _acquired perceptions of vision_, which are truly what give to vision its range of power, and without which the mere perception of colour would be of little more value than any other of the simplest of our sensations, I shall have an opportunity of pointing out to you some most important purposes, to which our muscular feelings are instrumental; and in the nicer analysis which I am inclined to make of the perceptions commonly ascribed to touch,--if my analysis be accurate--we shall find them operating at least as powerfully. At present, however, I speak of them merely as sources of animal pleasure or pain, of pleasure during moderate exercise and repose, and of pain during morbid lassitude, or the fatigue of oppression and unremitted labour.