have distinguished works of excellence on may perhaps appear, in their true character of every subject, have most probably had their infinity, to beings of a higher order, who may origin in that mathematical turn of thought, be able to distinguish as infinite, what our liwhich is now more prevalent than ever, and mited senses allow us to perceive only as finite. which gradually communicates itself even to They are one, not in nature, but in our thought; those who are ignorant of mathematics. It as one thousand individuals, that in nature must often happens that a single great man gives always be one thousand, receive a sort of unity the tone to the whole age in which he lives; that is relative merely to our conception, when and we must not forget, that the individual ranked by us a single regiment, or as many rewho has the most legitimate claim to the giments become one by forming together an glory of having introduced and established a army. In the congeries of external matter, new art of reasoning, was an excellent geome-the innumerable separate bodies are thus reter." The philosopher to whom this im-garded by us as one, when the space which provement of the art of reasoning is ascribed, is evidently Descartes, whose claim is certainly much less legitimate than that of our own illustrious countryman; but the works of Bacon were not very extensively studied on the continent, at the time at which Fontenelle wrote; while, especially in France, the splendid reputation of the great geometer who shook, as much with his own wild hypothesis, as with the weight of his reasoning, the almost idolatrous worship of the god of the schools, seemed to sweep before it the glory of every other reformer. The instance of Descartes, however, is a still more happy one than his ingenious countryman, who was himself a Cartesian, could have imagined it to be. It is, indeed, impossible to conceive a more striking example of that diffusive influence of the general spirit of scientific inquiry, which I wished to illustrate; since, in this instance, it survived the very system by which it was diffused; all that was sceptical in that mixed system of scepticism and dogmatism which constituted the general spirit of the philosophy of Descartes, having long continued, and even now continuing, to operate beneficially, when scarcely a doctrine of his particular phiosophy retains its hold. divides them is not measurable by our imperfect vision, and as distinct or separate, when the space can be measured by us. The unity of the aggregate is no absolute quality of the mass, but is truly relative to the observer's power of distinguishing the component parts; the mass being one or many, as his senses are less or better able to distinguish these. This whole globe of earth, with its oceans, and rivers, and mountains, and woods, and with all the separate multitudes of its animated inhabitants, may seem, to some being of another species, only one continuous and uniform mass; as the masses, that seem to us uniform and continuous, may seem a whole world of separate and varied parts, to the insect population that swarms upon its surface. "A single leaf of a tree," to borrow an obvious illustration from a French writer, "is a little world, inhabited by invisible animals, to whose senses it appears of immense extent, who see in it mountains and abysses that are almost immeasurable, and who, from one side of the leaf to the other, hold as little communication with the opposite animalculæ, who have their dwellings there, as we do with our antipodes."* Nothing can appear to our eyes more uniform than a piece of glass; yet we know, from its composition as a product of art, that it is a congeries of bodies, which have no similarity to each other, and which truly exist separately from each other, in the compound, as they existed separately before the composition, though the lines of space which divide them have now ceased to be visible to our weak organs; and though, instead of being composed of alkaline and silicious matter, which we know to be different in their qualities, the beautiful transparent substance, considered by us, were, as far as we knew, sim You will not then, I trust, take for granted, that precise notions as to the objects of inquiry, in any science, even in the department of external physics, can be absolutely without benefit to our plans of inquiry into mind, which must be pursued on the same principles, if it be pursued with any prospect of success; and I may, therefore, safely solicit your attention to a little farther elucidation of the two objects which we have in view, in general physical inquiry, whether it be relative to matter or to mind. To inquire into the composition of a sub-ple in the chymical sense of the term, it stance, is to consider as one, many substances, which have not the less an independent existence, because they are in immediate proximity to each other. What we term a body, however minute, is a multitude of bodies, or, to speak more exactly, an infinite number of bodies, which appear limited to us, indeed, but would still be as truly an aggregate of many bodies, not dissimilar, indeed, as in the former case, but each similar in qualities to the aggregate itself. The aggregate, in short, is, in every case, but a name invented by ourselves; and what we term the constituent elements, are all that truly exist. To inquire into the • Préface aux Eloges-Euvres, tom. v. p. 8. Fontenelle, Pluralité des Mondes, Conversat. 3. composition of a body is, therefore, only to inquire what those separate bodies are which we have chosen to consider as one, or rather which are ranked by us as one, from their apparent continuity. I have dwelt the longer on this point of the unity of an aggregate mass, as derived from the mind of the observer only, and not from its constituent bodies, which are truly separate and independent of each other, and must always be separate and independent, whatever changes they may seem to undergo, in the various processes of composition and decomposition, because this is one of the most simple, and, at the same time, one of the most convincing examples of a tendency of the mind, which we shall often have occasion to remark in the course of our intellectual analysis, the tendency to ascribe to substances without, as if existing in them like permanent physical qualities, the relations which ourselves have formed, by the mere comparison of objects with objects, and which, in themselves, as relations, are nothing more than modifications of our own minds. It is very difficult for us to believe, that, when we speak of a rock, or a mountain, or, perhaps, still more, when we speak of a single leaf or blade of grass as one, we speak of a plurality of independent substances, which may exist apart, as they now exist together, and which have no other unity than in our conception. It is the same with every other species of relation. The tallness of a tree, the lowliness of a shrub or weed, as these relative terms are used by us in opposition, do not express any real quality of the tree, or shrub, or weed, but only the fact that our mind has considered them together; all which they express, is the mere comparison that is in us, not any quality in the external objects; and yet we can scarcely bring our selves to think, but that, independently of this comparison, there is some quality, in the tree, which corresponds with our notion of tallness, and some opposite quality in the shrub or weed, which corresponds with our notion of shortness or lowliness; so that the tree would deserve the name of tall, though it were the only object in existence, and the shrub or weed, in like manner, the epithet of lowly, though it alone existed, without a single object with which it could be compared. These instances, as I have said, are simple, but they will not be the less useful, in preparing your minds for considering the more important notions of relation in general, that imply, indeed, always some actual qualities in the objects themselves, the perception of which leads us afterwards to consider them as related, but no actual quality in either of the objects that primarily and directly corresponds with the notion of the relation itself, as there are qualities of objects that correspond directly with our sensations of warmth or colour or any other of the sensations excited The immediately by external things. The relation is, in every sense of the word, mental, not merely as being a feeling of the mind, for our knowledge of the qualities of external things is, in this sense, equally mental, but, as having its cause and origin directly in the very nature of the mind itself, which cannot regard a number of objects, without forming some comparison, and investing them consequently with a number of relations. I have already spoken of the intellectual medium, through which external objects become known to us; and the metaphor is a just one. medium, in this case, as truly as in the transmission of light, communicates something of its own to that which it conveys; and it is as impossible for us to perceive objects long or often together, without that comparison which instantly invests them with certain relations, as it would be for us to perceive objects, for a single moment, free from the tint of the coloured glass through which we view_them. " Omnes perceptiones," says Lord Bacon, using a similar figure," omnes perceptiones, tam sensûs quam mentis, sunt ex analogia ho minis, non ex analogia universi; estque intellectus humanus instar speculi inæqualis ad radios rerum, qui suam naturam naturæ rerum immiscet, eamque distorquet et inficit." But, whatever may be thought of relations, in general, there can be no question, at least, as to the nature of that unity which we ascribe to bodies. We have seen, that the substance, which, in thought, we regard as one, is in truth, not one, but many substances, to which our thought alone gives unity; and that all inquiry, therefore, with respect to the nature of a substance, as it exists in space, is an inquiry into the nature of those separate bodies, that occupy the space which we assign to the imaginary aggregate. To dissipate this imaginary aggregate of our own creation, and to show us those separate bodies which occupy its space, and are all that nature created, is the great office of the analytic art of chymistry, which does for us only what the microscope does, that enables us to see the small objects, which are before us at all times, without our being able to distinguish them. When a chymist tells us, that glass, which appears to us one uniform substance, is composed of different substances, he tells us, what, with livelier perceptive organs, we might have known, without a single experiment; since the silicious matter and the alkali were present to us in every piece of glass, as much before he told us of their presence, as after it. The art of analysis, therefore, has its origin in the mere imperfection of our senses, and is truly the art of the blind, whose wants it is always striving to remedy, and always discovering sufficient proof of its inability to remedy them. We boast, indeed, of the chymical discoveries which we have made of late, with a ra pidity of progress as brilliant, as it is unexampled in the history of any other science; and we boast justly, because we have found, what the generations of inquirers that have preceded us on our globe, far from detecting, had not even ventured to guess. Without alluding to the agency of the galvanic power, by which all nature seems to be assuming before us a different aspect, we have seen fixed in the products of our common fires, and in the drossy rust of metals, the purest part of that ethereal fluid which we breathe, and the air itself, which was so long considered as simple, ceasing to be an element. Yet, whatever unsuspected similarities and diversities of composition we may have been able to trace in bodies, all our discoveries have not created a single new particle of matter. They have only shown these to exist, where they always existed, as much before our analysis as after it, unmarked indeed, but unmarked only because our senses alone were not capable of making the nice discrimination. If man had been able to perceive, with his mere organs of sense, the different particles that form together the atmospheric air-if he had at all times seen the portion of these which unites with the fuel that warms him, enter into this union, as distinctly as he sees the mass of fuel itself, which he flings into his furnace, he could not have thought it a very great intellectual achievement, to state in words so common and familiar a fact, the mere well-known change of place of a few well-known particles; and yet this is what, in the imperfect state of his perceptive organs, he so proudly terms his Theory of Combustion, the developement of which was hailed by a wondering world, and in these circumstances, justly hailed by it as a scientific era. To beings, capable of perceiving and distinguishing the different particles that form by their aggregation those small masses which, after the minutest mechanical division of which we are capable, appear atoms to us, the pride which we feel, in our chymical analyses, must seem as ludicrous, as to us would seem the pride of the blind, if one, who had never enjoyed the opportunity of beholding the sun, were to boast of having discovered, by a nice comparison of the changing temperature of bodies, that, during certain hours of the day, there passed over our earth some great source of heat. The addition of one new sense to us, who have already the inestimable advantages which vision affords, might probably, in a few hours, communicate more instruction, with respect to matter, than all which is ever to repay and consummate the physical labours of mankind; giving, perhaps, to a single glance, those slow revelations of nature which, one by one, at intervals of many centuries, are to immortalize the future sages of our race. "All philosophy," says an acute foreign writer, "is founded on these two things, that we have a great deal of curiosity, and very bad eyes. In astronomy, for example, if our eyes were better, we should then see distinctly, whether the stars really are, or are not, so many suns, illuminating worlds of their own; and if, on the other hand, we had less curiosity, we should then care very little about this knowledge, which would come pretty nearly to the same thing. But we wish to know more than we see, and there lies the difficulty. Even if we saw well the little which we do see, this would at least be some small knowledge gained. But we observe it different from what it is; and thus it happens that a true philosopher passes his life, in not believing what he sees, and in labouring to guess what is altogether beyond his sight. I cannot help figuring to myself," continues the same lively writer," that nature is a great public spectacle, which resembles that of the opera. From the place at which we sit in the theatre we do not see the stage quite as it is. The scenes and machinery are arranged, so as to produce a pleasing effect at a distance; and the weights and pulleys, on which the different movements depend, are hid from us. We therefore do not trouble our heads with guessing, how this mechanical part of the performance is carried on. It is perhaps only some mechanist, concealed amid the crowd of the pit, who racks his brain about a flight through the air, which appears to him extraordinary, and who is seriously bent on discovering by what means it has been executed. This mechanist gazing, and wondering, and tormenting himself, in the pit of the opera, is in a situation very like that of the philosopher in the theatre of the world. But what augments the difficulty to the philosopher, is, that, in the machinery which nature presents, the cords are completely concealed from him, so completely indeed, that the constant puzzle has been to guess, what that secret contrivance is, which produces the visible motions in the frame of the universe. Let us imagine all the sages collected at an opera,-the Pythagorases, Platos, Aristotles, and all those great names, which now-a-days make so much noise in our ears. suppose, that they see the flight of Phaeton, as he is represented carried off by the Winds; that they cannot perceive the cords to which he is attached; and that they are quite ignorant of every thing behind the scenes. It is a secret virtue, says one of them, that carries off Phaeton. Phaeton, says another, is composed of certain numbers, which cause him to ascend. A third says, Phaeton has a certain affection for the top of the stage. He does not feel at his ease, when he is not there. Phaeton, says a fourth, is not formed to fly; but he likes better to fly, than to leave the top of the stage empty, and a hundred other absurdities of the kind, that might have ruined the reputation of antiquity, if the reputation of antiquity for wisdom could have been ruin Let us ed. At last, come Descartes, and some other | Locke, and some other writers, have denomoderns, who say, Phaeton ascends, because minated passive power, to avoid the appahe is drawn by cords, and because a weight, rent verbal contradiction, or at least the ammore heavy than he, is descending as a coun- biguity, which may arise from annexing the terpoise. Accordingly, we now no longer be- term passive to a word, which is generally lieve, that a body will stir, unless it be drawn employed to signify, not the subject of change, or impelled by some other body, or that it but the cause or occasion of change. will ascend, or descend, unless by the operation of some spring or counterpoise; and thus to see nature, such as it really is, is to see the back of the stage at the opera.' In this exposition of the phenomena of the universe, and of those strange "follies of the wise," which have been gravely propounded in the systems of philosophers concerning them, there is much truth, as well as happy pleasantry. As far, at least, as relates to matter, considered merely as existing in space, the first of the two lights in which it may be physically viewed, there can be no question, that philosophy is nothing more than an endeavour to repair, by art, the badness of our eyes, that we may be able to see what is ac-parate bodies, to which ourselves give all the tually before us at every moment. To be unity which they have, merely by considering fairly behind the scenes of the great spectacle them as one. of nature, however, is something more than this. It is not merely to know, at any one moment, that there are many objects existing on the stage, which are invisible where the spectators sit, but to know them as pieces of machinery, and to observe them operating in all the wonders of the drama. It is, in short, to have that second view of nature, as existing in time as well as space, to the consideration of which I am to proceed in my next Lec Of these two points of view, then, in which an object may be regarded, when the question is put, What is it? we have seen, I hope, sufficiently distinctly, the nature of one. If, in answering the question, we regard the object merely as it exists in space, and say that it is a compound of certain substances, we mean nothing more, than that, in the portion of space, which we conceive to be occupied by this one imaginary aggregate, there is truly a plurality of bodies, which, though seemingly contiguous, have an existence, as separate and independent of each other, as if they were at the most remote distance; the one aggregate being nothing more than a name for these se ture. LECTURE VI. THE SAME SUBJECT CONTINUED. The necessity of inquiring into the nature of these separate elementary bodies,-which constitutes one of the two great departments of physical investigation, we found to arise from the imperfection of our senses, that are not sufficiently acute to discover, of themselves, the component parts of the masses, which nature everywhere presents to us. We are thus obliged to form to ourselves an art of analysis, merely that we may perceive what is constantly before our eyes, in the same manner as we are obliged to have recourse to the contrivances of the optician, to perceive stars www.and planets, that are incessantly shedding on us their light. IN my last Lecture, Gentlemen, I considered, at some length, the nature of Physical Inquiry in general, and stated to you, in particular, the two lights, in which objects may be physically viewed, as existing simply in space, or as existing in time; the inquiries, with respect to the one, having regard to the composition of bodies; the inquiries, with respect to the other, having regard to the changes, of which they are either the subjects or occasions, and consequently to their susceptibilities or their powers-their susceptibilities of being affected by other substances, their powers of affecting other substances. I use the word susceptibility, you will perceive, as in this case synonimous with what Mr • Fontenelle, Pluralité des Mondes, Conversat. 1. There is, indeed, something truly worthy of our astonishment, in the sort of knowledge of the qualities of matter, which, with our very imperfect senses, we are still able to attain. What we conceive ourselves to know is an aggregate of many bodies, of each of which, individually, we may be said, in the strictest sense of the term, to be absolutely ignorant; and yet the aggregate, which we know, has no real existence, but as that very multitude of bodies, of which we are ignorant. When water was regarded as a simple substance, every one, who looked upon a lake or a river, conceived that he knew as well what the liquid was which flowed in it as the chymist, who now considers it as compound; and the chymist who has learned to regard it as compound, is perhaps as ignorant of the true nature of the separate bodies that exist in it, as those who formerly regarded it as simple; since one additional discovery may prove the very elements, which he now regards as the ultimate constituents of water, to be truly compounded of other elements, still more minute, and now altogether unknown to him. That our only knowledge of matter should be of a multitude of bodies, of the nature of each of which, individually, we are in absolute ignorance, may seem, at first sight, to justify many of the most extravagant doubts of the sceptic: and yet there is really no ground for such scepticism, since, though the co-existing bodies be separately unknown, the effect, which they produce when co-existing in the circumstances observed by us, is not the less certain and definite; and it is this joint effect of the whole, thus certain and definite, which is the true object of our knowledge; not the uncertain effect, which the minuter elements might produce, if they existed alone. The same aggregates, whatever their elementary nature may be, operate on our senses, as often as they recur, in the same manner; the unknown elements which constitute an oak, or a tower, or the ivy that clings around it, exciting in the mind those particular sensations to the external causes of which we continue to give the name of oak, or tower, or ivy; and exciting these, as precisely and uniformly as if we were acquainted with each minute element of the objects without. Our knowledge of nature must, in this way, indeed, be confined to the mixed effects of the masses which it exhibits; but it is not on that account less valuable, nor less sure; for to the certainty of this limited knowledge all which is necessary is uniformity of the mixed effects, whatever their unknown co-existing causes may be. It is with masses only, not with elements, that we are concerned, in all the important purposes of life; and the provident wisdom of the Author of Nature, therefore, has, in this as in every other case, adapted our powers to our necessities,-giving to all mankind the knowledge that is requisite for the purposes which all mankind must equally have in view, and leaving, to a few philosophic inquirers, the curiosity of discovering what the substances around us truly are in their elementary state, and the means of making continual progress in this never-ending analysis. Such then is the nature of one of the views in which physical inquiry may be directed, to the discovery of elements, that are existing together, at the same moment. But is not this species of inquiry, it may be asked, peculiar to matter, or may it also be extended to mind? It is easy to conceive that, if matter always have extension, and therefore necessarily be composed of parts, an inquiry into its composition may form an important part of physical investigation; but this sort of inquiry will seem to you altogether inadmissible in the philosophy of mind, since the mind is not composed of parts that co-exist, but is simple and indivisible. If, indeed, the term composition, in this application of it, be understood strictly in the same sense as when applied to matter, it is very evident, that there can be no inquiry into the composition of thoughts and feelings, since every thought and feeling is as simple and indivisible as the mind itself; being, in truth, nothing more than the mind itself existing at a certain moment in a certain state; and yet, in consequence of some very wonderful laws which regulate the successions of our mental phenomena, the science of mind is, in all its most important respects, a science of analysis, or at least a science which exhibits to our contemplation the same results as if it were strictly analytical; and we inquire into the separate ideas or other feelings, involved in one complex thought or emotion, very nearly as we inquire into the corpuscular elements that co-exist in one seemingly continuous mass. The nature of this very wonderful application of analysis, or at least of a process which is virtually the same as analysis, to a substance, that is necessarily at all times simple and indivisible, will, however, be better understood, by you, after we have turned our attention to the other general division of physical inquiry, which is still to be considered by us. I need not, I hope, repeat, after the remarks which I made in my last Lecture, that, in leading your thoughts, for so long a time, to the subject of general science, I have had constantly in view its application to the phenomena of our own department of it, and that we are truly learning to study mind with accuracy, when we are learning what it is, which is to be studied in the great system of things. There can be no question at least, that he who has erroneous notions of the objects of physical investigation in the material universe, will be very likely also to err, or rather cannot fail to err, in his notions of the objects of physical investigation, as it relates to mind. I proceed, then, to consider, what it is which we truly have in view, when we direct our inquiry, not to the mere composition of objects existing continuously in space, but to the suc cession of changes which they exhibit in time; to their susceptibility of being affected by other substances, or their power of affecting other substances. The inquiry, as you must perceive, involves the consideration of some words about which a peculiar mystery has been very generally supposed to hang-causation, power, connexion of events. But we shall perhaps find that what is supposed so peculiarly mysterious in them, is not in the very simple notions themselves, but in the misconceptions of those who have treated of them. It is not in this case, as in the former department of physical investigation, the mere imperfection of our senses, that produces the necessity of inquiry. Matter, as existing in space, is wholly before us, and all which is necessary for perfect knowledge of it, in this respect, is greater delicacy of our perceptive organs, that we may distinguish every element of the seemingly continuous mass. To know the mere composition of a substance, is to know only what is actually present at the |