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 mind. 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 lowness 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 ourselves 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 lowness; 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 natures 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 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. The 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 sensus quam mentis, sunt ex analogia hominis, 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 Chemistry, 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 chemist 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 siliceous 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 chemical discoveries which we have made of late, with a rapidity 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 chemical 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 a very little about