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would be at our feet; and it would be vain, therefore, to expect that ardour of soul, which is kindled, amid the hopes and the fears, the tumult and the competition of the chase.

"If man were omnipotent, without being God," says Rousseau, "he would be a miserable creature: he would be deprived of the pleasure of desiring; and what privation would be so difficult to be borne !" It may be said, at least with equal truth, that, if man were omniscient, without the other perfections of the Divinity, he would be far less happy than at present. To infinite benevolence, indeed, accompanied with infinite power, a corresponding infinity of knowledge must afford the highest of all imaginable gratifications, by its subservience to those gracious plans of good, which are manifested in the universe, and which, in making known to us the existence of the Supreme Being, have made him known to us as the object of grateful love and admiration. But if, in other respects, we were to continue as at present, with our erring passions, and moral weaknesses of every sort,-to be doomed to have nothing to learn, would be a punishment, not a blessing. In such circumstances, if they were to continue for ever, the annihilation of our intellectual being would not be an evil so great, as the mere extinction of our curiosity, and of all the delights and consolations which it affords, not merely when we gratify it, but when we are merely seeking to gratify it.

"Else wherefore burns,

In mortal bosoms, this unquenched hope

That breathes from day to day sublimer things,

And mocks possession! Wherefore darts the mind,

With such resistless ardour, to embrace

Majestic forms, impatient to be free,

Proud of the strong contention of her toils,

Proud to be daring?"*

'Why departs she widet
From the dull track and journey of her times,
To grasp the good she knows not? In the field
Of things which may be, in the spacious field
Of science, potent arts, or dreadful arms,
To raise up scenes, in which her own desires
Contented may repose,-when things which are
Pall on her temper like a twice told tale."

It is sufficient, that we are endowed with powers of discovery. Our gratitude is due to Heaven for the gift; and the more due for that gracious wisdom, which has known how to limit the powers which it gave, so as to produce a greater result of good by the very limitation. Our prejudices, which sometimes forbid reasoning, and the errors, to which our imperfect reasoning often leads us, we should consider, when all their remote relations are taken into account, as indirect sources of happiness; and though we may wish, and justly wish, to analyze them, and to rise above their influence, -for, without this exertion, and consequent feeling of progress, on our part, they would be evil rather than good,-we must not forget, that it is to them we owe the luxury, which the immediate analysis affords, and the acquisition of the innumerable truths, which the prevalence of these errors, in past ages, has left to be discovered by the ages which succeeded.

In this, and in every thing which relates to man, Nature has had in view,

* Pleasures of Imagination, (first form of the poem,) B. i. v. 166–171. 173—5.

Why departs the soul

Wide from the track.-Orig.

Pleasures of Imagination, (second form of the poem,) B. i. v. 213–220.

So much, indeed, of human knowledge, and of all that is valuable and delightful in human feeling, involves these elementary sensations, as it were, in the very essence of the thoughts and feelings themselves, that one of the most acute of modern French metaphysicians, and, with scarcely an exception, all the philosophers of the French metaphysical school, who are his followers, have considered the whole variety of human consciousness, as mere sensations variously transformed; though, in stating the nature of this transformation, and the difference of the sensations as transformed from the primary forms of mere external feeling, they have not been so explicit, as the assertors of a system so paradoxical ought assuredly to have been. On the fallacies of this very prevalent theory of mind, however, which is afterwards to be examined by us fully, I need not at present make any remarks.

Though this excessive simplification of the phenomena of human thought and feeling is, however, far more than the phenomena truly allow, it is not the less certain, that all the varieties of our consciousness, though not mere transformations of external sense, are, when traced to their source, the results of sensation, in its various original forms. In inquiring into the phenomena of our senses, then, we begin our inquiry, where knowledge itself begins, and though the twilight, which hangs over this first opening of intellectual life, is perhaps only a presage, or a part of that obscurity which is to attend the whole track of human investigation, it still is twilight only, not absolute darkness. We can discover much, though we cannot discover all; and where absolute discovery is not allowed, there is still left to us a probability of conjecture, of which, in such limited circumstances, even philosophy may justly avail herself, without departing from her legitimate province.

LECTURE XIX.

BRIEF NOTICE OF THE CORPOREAL PART OF THE PROCESS, IN

SENSATION.

THE mental phenomena, of the class which is at present under our consideration, being those, which arise in consequence of certain previous affections of our organs of sense, it is necessary, that we should take some notice of the corporeal part of the process; though it must always be remembered, that it is the last part of the process, the mental affection only, which truly belongs to our science, and that, if this in all its varieties, had been the result of any other species of affections of organs constituted in any other manner, as long as there was the regular correspondence of certain mental affections with certain organic affections, the philosophy of mind would have continued precisely the same as now. Our systems of anatomy, and of the physiology of our mere bodily frame, would indeed have been different, but not that more intimate physiology, which relates to the functions of the animating spirit, whose presence is life, and without which our bodily frame, in all its beautiful adaptation of parts to parts, is a machine, as inert and powerless, as the separate atoms that compose it.

The great essential organ of all sensation is the brain, with its appendages,

strength, even in being vanquished. "Studiorum salutarium, etiam citra effectum, salutaris tractatio est." If she has placed us in a labyrinth, she has at the same time furnished us with a clue, which may guide us, not indeed through all its dark and intricate windings, but through those broad paths, which conduct us into day. The single power by which we discover resemblance or relation in general, is a sufficient aid to us, in the perplexity and confusion of our first attempts at arrangement. It begins, by converting thousands, and more than thousands, into one, and, reducing, in the same manner, the numbers thus formed, it arrives at last at the few distinctive characters of those great comprehensive tribes, on which it ceases to operate, because there is nothing left to oppress the memory, or the understanding. If there had been no such science as chemistry, who could have ventured to suppose, that the innumerable bodies, animate and inanimate, on the surface of our globe, and all, which we have been able to explore in the very depths of the earth itself, are reducible, and even in the imperfect state of the science, have been already reduced, to a few simple elements? The science of mind, as it is a science of analysis, I have more than once compared to chemistry, and pointed out to you, and illustrated, its various circumstances of resemblance. In this too, we may hope the analogy will hold, that, as the innumerable aggregates, in the one science, have been reduced and simplified, the innumerable complex feelings in the other will admit of a corresponding reduction and simplification.

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The classes which we form, in the mental as well as in the material universe, depend, as you cannot but know, on certain relations which we discover in the phenomena; and the relations according to which objects may be arranged, are of course various, as they are considered by different individuals in different points of view. Some of these relations present themselves immediately, as if to our very glance; others are discoverable only after attentive reflection;—and though the former, merely as presenting themselves more readily, may seem, on that account, better suited for the general purpose of arrangement, it is not the less true that the classification which proaches nearest to perfection, is far from being always that which is founded on relations, that seem at first sight the most obvious. The rudest wanderer in the fields may imagine, that the profusion of blossoms around him,—in the greater number of which he is able, himself, to discover many striking resemblances,—may be reduced into some order of arrangement. But he would be little aware, that the principle according to which they are now universally classed, has relation, not to the parts which appear to him to constitute the whole flower, but to some small part of the blossom, which he does not perceive, at the distance at which he passes it, and which scarcely attracts his eye, when he plucks it from the stem.

To our mental classifications the remark is equally applicable. In these too, the most obvious distinctions are not always those which answer best the purposes of systematic arrangement. The phenomena of the mind are only the mind itself existing in certain states; and as many of these states are in their nature agreeable, and others disagreeable, this difference, which is to the sentient being himself the most important of all differences, may be supposed to afford the most obvious principle of classification. (What is plea-. sant, what is painful, are perhaps the first classes, which the infant has formed long before he is capable of distinguishing them by a name; and the very imbecility of idiotism itself, to which nothing is true or false, or right or

answered exactly the same end; which is as much as to say, that our ignorance on the subject is complete. The only physiological facts of importance, in reference to sensation, are, that if the nerves, which terminate in particular organs, be greatly diseased, the sensations which we ascribe to those particular organs cease; and cease, in like manner, if the continuity of the nerves be destroyed, by cutting them in any part of their course, or if, without loss of absolute continuity, their structure, in any part of their course be impaired by pressure, whether from tight ligatures drawn round them for the purpose of experiment, or from natural morbid causes. In short, if the brain and nerves be in a sound state, and certain substances be applied to certain parts of the nervous system,—as, for instance, sapid bodies to the extremities of the nerves of taste, or light to that expansion of the optic nerve, which forms what is termed the retina,-there is then instant sensation; and when the brain itself is not in a sound state to a certain extent, or when the nerve which is diffused on a particular organ is, either at this extremity of it, or in any part of its course, to a certain degree impaired, then there is no sensation, though the same external causes be applied. This very slight general knowledge of the circumstances in which sensation takes place, and of the circumstances in which it does NOT take place, is all the knowledge which physiology affords us of the corporeal part of the process;and it is likely to continue so for ever,—at least in all the more important respects of our ignorance, since any changes which occur in the corpuscular motion, and consequent new arrangement of the particles of the substance of the brain and nerves, corresponding with the diversities of feeling during those particular states,-if such corpuscular motions or changes do really take place,-are probably far too minute to be observable by our organs; even though we could lay open all the internal parts of the brain to complete observation, without destroying, or at all affecting, the usual phenomena of life :

"In following life through creatures we dissect,
We lose it, in the moment we detect."

Indeed, we are not able to do even so much as this; for life has already vanished, long before we have come upon the verge of its secret precincts. It is like a Magician, that operates at a distance on every side, but still keeps himself apart, within a narrow circle. If we remain without the circle, we may gaze with never-ceasing admiration, on the wonders that play in rapid succession before our eyes. But, if we rush within, to force an avowal of the secret energy that produces them, the enchanter and the enchantments alike are fled.

The brain, then, and the various nerves of sense in continuity with it, may, when taken together, be considered as forming one great organ, which I would term briefly the sensorial organ, essential to life, and to the immediate production of those mental phenomena which constitute our sensations, and, perhaps, too, modifying in some measure, directly or indirectly, all the other phenomena of the mind.

"Dum mens alma caput cerebrique palatia celsa
Occupat, et famulos sublimis dirigit artus,
Et facili imperio nervorum flectit habenas,
Illius ad nutum sensus extranea rerum
Explorant signa, et studio exemplaria fido

Ad dominam adducunt; vel qui statione locantur
Vicina, capitisque tuentur limina, ocelli,
Naresque, auriculæque, et vis arguta palati;
Vel qui per totam currit sparso agmine molem
Tactus, ad extremas speculator corporis aras.
His sensim auxiliis instructa fidelibus, olim
Mens humilis nulloque jacens ingloria cultu
Carceris in tenebris mox sese attollit in auras
Dives opum variarum, et sidera scandit Olympi."

Of the nature of the connexion of this great sensorial organ with the sentient mind, we never shall be able to understand more than is involved in the simple fact, that a certain affection of the nervous system precedes immediately a certain affection of the mind. But, though we are accustomed to regard this species of mutual succession of bodily and mental changes, as peculiarly inexplicable, from the very different nature of the substances which are reciprocally affected, it is truly not more so than any other case of succession of events, where the phenomena occur in substances that are not different in their properties, but analogous, or even absolutely similar; since, in no one instance of this kind, can we perceive more than the uniform order of the succession itself; and of changes, the successions of which are all absolutely inexplicable, or, in other words, absolutely simple, and unsusceptible, therefore, of further analysis, none can be justly said to be more or less so than another. That a peculiar state of the mere particles of the brain should be followed by a change of state of the sentient mind, is truly wonderful; but if we consider it strictly, we shall find it to be by no means more wonderful, than that the arrival of the moon, at a certain point of the heavens, should render the state of a body on the surface of our earth, different from what it otherwise would naturally be, or that the state of every particle of our globe, in its relative tendencies of gravitation, should be instantly changed, as it unquestionably would be, by the destruction of the most distant satellite of the most distant planet of our system, or probably too, by the destruction even of one of those remotest stars, which are illuminating their own system of planets, so far in the depth of infinity, that their light,-to borrow a well-known illustration of sidereal distance,―may never yet have reached our earth, since the moment at which they darted forth their first beams, in the creation of the universe. We believe, indeed, with as much confidence, that one event will uniformly have for its consequent another event, which we have observed to follow it, as we believe the simple fact that it has preceded it, in the particular case observed. But the knowledge of the present sequence, as a mere fact, to be remembered, and the expectation of future similar sequences, as the result of an original law of our belief, are precisely of the same kind, whether the sequence of changes be in mind, or in matter singly, or reciprocally in both.

What the nature of the change is, that is produced at the extremity of the nerve, it is beyond our power to state, or even to guess; and we are equally ignorant of the manner in which this affection of the nerve is communicated, or is supposed to be communicated, to the brain. But that some affection is gradually propagated, from the one to the other, so as to render the change in the state of the brain subsequent, by a certain interval, to the change in the state of the nerve, is universally believed. In applying to this change the term impression, a term indeed which had been in common use before, Dr. Reid is careful to point out the reason for which this term appears to