of exertion. Irritation, sensation, volition, and association, are no sensorial power: they are only its modes, or qualities. When a fibre is contracted, sensorial power is not communicated to the fibre, but simply motion, which is a necessary consequence of a certain state of sensorial power. The motion, indeed, perishes; but the motion is a state of the fibre, the effect of a state of sensorial power, and of that state only for sensorial power existed in the organ, without affecting it, previously to the application of the stimulus. When the contraction of the fibre has ceased, we are entitled to infer, that the cause of the contraction has ceased; but we are not entitled to infer more. The cause of contraction was not the simple existence of sensorial power, but its existence, in a certain state; and we may, therefore, justly infer, that it has returned to the state, in which it existed, before the action of the stimulus. If, by the expenditure of sensorial power, nothing more be meant, than a slight change of its place in the system, this may be admitted, without adding much strength to Dr. Darwin's theory. Thus, when the vessels of the brain are stimulated by the blood, the spirit of animation may be allowed to quit the fibres, which it caused to contract; but no reason can be adduced, to prove, that it is wholly lost, which will not equally prove, that the quantity, secreted by the brain, quits the sensorium, immediately after secretion, instead of being distributed to the different fibres of the system. When sensation is propagated along a nerve, the sensorial power, in the centre of the nerve, is expended; but it ceases not to exist, and we have no reason to suppose, that the membrane of the nerve suddenly becomes per meable to sensorial power, and suffers it to escape from the system. If, therefore, the general quantity of the spirit of animation be not diminished by exertion, and if, at the same time, a continual supply of that fluid be secreted, the fibrous motions must continually increase in violence; and those phenomena, which seem to proceed from deficiency of strength, are thus wholly inexplicable, on the principles of the sensorial theory. 6 The ingenious author of that theory himself considers exertion, as, in some instances, attended with an increase, rather than a diminution, of sensorial power. This, he observes, "sometime, happens from the exhibition of opium and of wine," Vol. II. p. 363; and, when the vessels of the skin are exposed to great heat, an excess of sensorial power is produced in them, which is derived thither by the increase of stimulus above what is natural," Vol. II. p. 321. No reason can be shown, that the application of heat to the skin should be attended with an increase of sensorial power, which will not prove, that this increase should be the effect of every stimulus. In that case, no bounds can be fixed. The spirit of animation, whether exerted, or at rest, is accumulated in the organs; and violent inflammation, or palsy, must, according to Dr. Darwin, be, in a few hours, the inevitable consequence of life.' Mr. Brown afterward proceeds to shew the difficulties, on the principles of the Zoonomia, attending the supposition that the expenditure of sensorial power is proportioned to the degree of of the stimulus applied. According to his usual process, he then proves that, even conceding these points to the author, the doctrine will not account for the phænomena of animal life. As this subject forms so important a part of the Zoonomia, we shall extract his principal remarks: If inaction induce an accumulation of sensorial power, the most indolent should be the most capable of labour, and exercise be, in consequence, hurtful, as it diminishes the general quantity of the spirit of animation. If it be said that the secretion in the brain is proportionally increased, by the greater quantity of oxygene, inspired during exercise, the impossibility of fatigue, in these circumstances, will be a sufficient answer. If the secretion be precisely equal to the expenditure, the fibres will continue, in the same state, as before exertion, and, if it be greater, the secretion will continue, in an increasing ration; so that the fibres will be excited to unnatural action by their accustomed stimuli. But the quantity secreted is not equal to that expended; for fatigue is the invariable consequence of violent exercise. No benefit, therefore, will be derived to the system; but, on the contrary, general debility must ensue: for the spirit of anima. tion, in the brain, being less, will secrete a less supply. The circulation being slower, less oxygene will be combined with the blood, and the vital functions be thus, more and more, impeded, by the increas ing reaction of direct, and indirect debility. If it be said, that, though violent exercise may induce weakness, it, notwithstanding, when used with moderation, invigorates the system, the truth of the observation will be admitted; but Dr. Dar. win's theory must, at the same time, be abandoned, Let us suppose the exercise to continue, during a certain number of hours. The spirit of animation, it is conceived, though diminished, at the end of that period, is not diminished, at the end of the first hour. If it be merely equal to the original quantity, the exercise may be indefinitely continued, without producing strength, or weakness; and, if it be greater, the causes of accumulation increasing, the sensorial power will be much more abundant, when the hours have elapsed; or, in other words, the fibres will not be fatigued. The indolent, and sedentary, instead of being subject to nervous fevers, should, on this hypothesis, be subject to continual attacks of inflammatory fever: for, during their inactivity, the spirit of animation must be accumulated, in so great a degree, as to render the slightest irritation insupportable.' On the subject of Sensual Motions, the author has combated the account given in Zoonomia of the immediate organs of sense; and we find, in this section, a command of language and a variation of style, which evince that Mr. Brown has not always confined himself within the thorny maze of metaphysics: No subject is so interesting to our curiosity, as the nature of those feelings, which connect us with the world, and in which our happiness, 7 happiness, or misery, consists; nor is there any, in which we have derived less aid from the wisdom of past ages. The consciousness of thought is implied in the consciousness of existence; yet we are still as unacquainted with the mode, in which this mental change is carried on, as we were, before the first philosophic savage had wondered at himself. The phantasms, and species, and ideas, of the ancient schools no longer delude us with the belief of knowledge; and all, we have learned, has served only to add to the difficulty of unlearning error. What is this subtile feeling, we have still to ask, so variable, yet ever present; which elevates us to the rank of gods, or degrades us below the dull insensibility of the earth, on which we tread? The bubble still floats before our eyes, gay with all the variety of light; but what delicate touch shall retain it in expansion, and arrest its fleeting colours? The author of the Botanic Garden, who so happily succeeded, in" enlisting imagination under the banner of science," a design, easy only to powers like his, is not content, to have enlarged our acquaintance with the objects around us. Undeterred by the failure of his predecessors, he has attempted "The doubtful task, To paint the finest features of the mind, The immediate organs of sense, according to the theory proposed, are not expansions of their peculiar nervous medulla, but are composed of fibres, intermixed with sensorial power. They are stimulated to contraction, like the muscular fibres, from which they differ, in possessing a greater proportional quantity of the vital spirit. The motions of these fibres constitute our ideas; and, when an organ is destroyed, the ideas of that organ necessarily perish. Can we then suppose, that Milton described the beauties of his ideal paradise, without any conception of what he described; or, that unconscious of any loss, he could mourn, with so much apparent feeling, his insensibility of Day, or the sweet approach of ev'n, or morn, Or sight of vernal bloom, or summer's rose, Or flocks, or herds, or human face divine?" could the fox, RIS" of Homer, to use the words of Dr.Darwin— the long shadow of the flying javelin-have been elegantly designed, "to give us an idea of its velocity, and not of its length," when the poet himself was incapable of the idea. We might, with as much reason, expect, that the rude materials of a building, ignorantly thrown together, should rise into a model of perfect architecture. If the lively descriptions of visual objects, which delight, and astonish us, in the poems of Homer, and Milton, have been produced by the total ab sence of ideas, who will not abjure the useless pomp of knowledge? "Where ignorance is bliss, 'Tis folly to be wise." * Pleasures of Imagination, Book I. 1. 45.' Mr. Brown observes, that Dr. D. has differed from other metaphysicians in his definition of an idea, in confining his definition to one part of the process; the motion of certain fibres : for all admit that a certain change of the organ precedes the change of the mind. Yet Dr. Darwin, deceived, as in other cases, by its former signification, uses the term idea also to express a state of the spirit of animation. For the arguments by which the author proves the distinction between our ideas and fibrous motions, we must refer to the work. In the course of them, Mr. Brown has introduced a defence of the Berkeleyan doctrine of general ideas; in which we are surprised to observe no indications of an acquaintance with Mr. Horne Tooke's opinions concerning general terms. The dissimilarity between ideas and fibrous motions is farther illustrated, in the section on the production of ideas: • When the idea of a cup is in the sensorium, a similar concave must exist, in the organ of touch. The sensorial power must be absent, within the circumference of the idea; so that, though the surface be pierced, no sensation should ensue. Yet, even when a larger concave is the subject of our thought, as a cave, or a valley, a slight puncture is sufficient to recall our attention to the objects around us. To the idea of a concave surface nothing more is necessary, than the existence of a similar retrocession of the spirit of animation, in the sensorium. But, as that fluid cannot rise above the surface of the skin, a convexity of sensorial power can be formed, only by the general, or partial retrocession of the sensorial power around it. In the former case, the whole of the remaining surface of the body must be insensible in the latter, the idea of the convex surface cannot exist, without the idea of another ascending surface, and of an intermediate concavity. The ideas, which Dr. Darwin ascribes to touch, instead of approaching to infinity, are limited by his theory to a small class. Though every nerve of the system be, at the same moment, compressed, and though each compression be perceived, our ideas of figure must be bounded by the extent of the spirit of animation. We may, indeed, “ inspect a mite;" but we cannot "comprehend the heaven." We may view, as a whole, the humbler plant; but a tree will tower above the most expanded sensorium. The dwarf may look down on others, more diminutive than himself; but, though the age of giants were to return, they would not appear to him larger, than the two feet dimensions of his own mind. When a body is pressed violently against the organ of touch, so as to excite a large concavity, pain ensues, and the effect should be similar in imagination; yet we do not feel pain, when we think of a mountain, or a valley. Even if the theory advanced were free from other objections, the point, which it takes for granted, remains to be proved; that the compressed organ resembles the compressing body. The reverse will be found found to be the case. Pressed by a convex surface, that of the orof touch is concave, and should, therefore, form the idea of a concave body. gan The second mode of acquiring the ideas of the length, and breadth of objects by the continuance of their pressure on our moving organ of touch, is liable to all the objections of the former mode, and to others, from which it is free. By the continuance of the pressure, I suppose, is meant the time, in which, moving with the same velocity, the hand passes from one extremity to the other. It is as difficult, however, to measure velocity, as length. Time we measure, by the comparison of our ideas; so that, in this case, we must remain ignorant of the continuance of time, as there are not two ideas to be compared. The same fibres of the organ of touch are, during the whole process, contracted, in the same manner, and, therefore, form one idea. The sensorial motion would be the same, if a body, equal in size to the palm of my hand, were, during a certain interval, pressed against its surface. The ideas of motion, time, place, space, and number, are stated to be modes of figure; and the explanation of their origin must, therefore, be liable to all the preceding objections.' Dr. Darwin's classification of ideas as irritative, sensitive, voluntary, and associate, is condemned as too complex:-Mr. B. is of opinion that perception and association seem to be the only modes in which ideas exist. In the section on the Animation of Vegetables, we find many valuable observations on the mistakes incurred by philosophers from the imperfection of language: but for these, and for the writer's ingenious objections to the vitality and intellectual powers which Dr. Darwin has bestowed on the vegetable tribes, with a partiality which is laudable perhaps in the author of the Botanic Garden, we must advise our readers to consult the performance itself; and we must here close it for the present, intending to return to it in our next Number. [To be continued.] ART. IX. Medical Records and Researches, selected from the Papers of a private Medical Association. Vol. I. Part I. 8vo. pp. 288. 78. 6d. Boards. Robinsons. 1798. TH HIS is a respectable collection of cases and observations, furnishing an additional proof of the utility of free communication among medical men engaged in actual practice. A re-union of experience is produced by establishments of this nature, which sometimes throws unexpected light on difficult. subjects; and the spirit of active inquiry, which they support, diffuses its benefits through the practice of every individual engaged in them.-As all the papers contained in such an assem blage |