The Cosmos of Humboldt has the ambitious aim of presenting to us the universe, so far as we know it, in that beauty of harmony which results from a whole. Thus, at least, we understand his intention. He would domineer, as with an eagle's glance, over the known creation, and embrace it in its unity, displaying to us that beauty which exists in the harmony of all its parts. The attempt no one would depreciate or decry, but manifestly the imperfect state of science forbids its execution. We have attained no point of view from which we can survey the world as one harmonious whole. Our knowledge is fragmentary, uncertain, imperfect; and the most philosophic mind cannot reduce it into any shape in which it shall appear other than uncertain and fragmentary. We cannot "stand in the sun," as Coleridge says in his fine verse, and survey creation; we have no such luminous standing-point. There never, indeed, was a time when the attempt to harmonise our knowledge, and view the universe of things "in the beauty of unity," was so hopeless, so desperate. For the old theories, the old methods of representing to the imagination the more subtle and invisible agencies of the physical world, are shaken, or exploded, and nothing new has been able to take their place. What is new, and what is old, are alike unsettled, unconfirmed. In reality, therefore, the work of Mrs Somerville is as much a Cosmos as that of Von Humboldt; and, as a work of instruction, is far better for not aiming higher than it does. Mrs Somerville presents to us each gospel of science—if we may give that title to its imperfect revelations—and does not bewilder or confuse by attempting that "harmony of the gospels" which the scientific expositor is, as yet, unable to accomplish.
As yet, we have said—but, indeed, will science be ever able to realise this aspiration of the intellect after unity and completeness of view? To the reflective mind, human science presents this singular aspect. Whilst the speculative reason of man continually seeks after unity, strives to see the many in the one—as the Platonist would express himself—or, as we should rather say, strives to resolve the multiplicity of phenomena into a few ultimate causes, so as to create for itself a whole, some rounded system which the intellectual vision call embrace; the discoveries of science, by which it hopes and strives to realise this end, do in fact, at every stage, increase the apparent complexity of the phenomena. The new agencies, or causes, which are brought to light, if they explain what before was anomalous and obscure, become themselves the source of innumerable difficulties and conjectures. Each discovery stirs more questions than it sets at rest. What, on its first introduction, promised to explain so many things, is found, on further acquaintance, to have added but one more to the inexplicable facts around us. With each step, also, in our inquiry, the physical agents that are revealed to us become more subtle, more calculated to excite and to elude our curiosity. Already, half our science is occupied with matter that is invisible. From time to time some grand generalisation is proposed—electricity is now the evoked spirit which is to help us through our besetting difficulties—but, fast as the theory is formed, some new fact emerges that will not range itself within it; the cautious thinker steps back, and acknowledges that the effort is as yet premature. It always will be premature.
There is a perpetual antagonism between the intellectual tendency to reduce all phenomena to a harmonious and complete system, and that increase of knowledge which, while it seems to favour the attempt, renders it more and more impracticable. With our limited powers, we cannot embrace the whole; and therefore it must follow, that it is only when our knowledge is scanty, that we seem capable of the task. Every addition to that knowledge, from the time that Thales would have reduced all things to the one element of water, has rendered the task more hopeless. And as science was never so far advanced as at the present time, so this antagonism was never so clearly illustrated between the effort of reason to generalise, and the influx of broken knowledge, reducing the overtasked intellect to despair. How much has lately been revealed to us of the more subtle powers and processes of nature—of light, of heat, of electricity! How tempting the generalisations offered to our view! We seem to be, at least, upon the eve of some great discovery which will explain all: an illusion which is destined to prompt the researches of the ardent spirits of every age. They will always be on the eve of some great discovery which is to place the clue of the labyrinth into their hand. The new discovery, like its predecessor, will add only another chamber to the interminable labyrinth.
Let us, for instance, suppose that we have discovered, in electricity, the cause of that attraction to which we had confided the revolution of the planets; of that chemical affinity to which we had ascribed the various combinations of those ultimate atoms of which the material world is presumed to be composed; of that vital principle which assimilates in the plant, and grows and feels in the animal. Let us suppose that this is a sound generalisation; yet, as electricity cannot be alone both attraction in the mass, and chemical affinity in the atom, and irritability and susceptibility in the fibre and the nerve, what has the speculative reason attained but to the knowledge of a new and necessary agent, producing different effects according to the different conditions in which, and the different co-agencies with which it operates? These conditions, these co-agencies, are all to be discovered. It is one flash of light, revealing a whole world of ignorance.
To the explanation of the most obstinate of all problems—the nature of the vital principle—we seem to have made a great step when we introduce a current of electricity circulating through the nerves. If this hypothesis be established, we shall probably have made a valuable and very useful addition to our stock of knowledge; but we shall be as far as ever from solving the problem of the vital principle. We have now a current of electricity circulating along the nerves, as we had before a current of blood, circulating through the veins and arteries; the one may become as prominent and as important a fact in the science of the physician as the other; but it will be equally powerless with the old discovery of Harvey to explain the ultimate cause of vitality. To the speculative reason it has but complicated the phenomena of animal life.
Within the memory of a living man, there has been such progress and revolution in science, that not one of the great generalisations taught him in his youth can be now received as uncontested propositions. Not many years ago, how commodiously a few words, such as attraction, caloric, affinity, rays of light, and others, could be used, and how much they seemed to explain! Caloric was a fluid, unseen indeed, but very obedient to the imagination—expanding bodies, and radiating from one to the other in a quite orderly manner. What is it now? Perhaps the vibration of a subtle ether interfused through all bodies; perhaps the vibration of the atomic parts themselves of those bodies. Who will venture to say? Attraction and affinity are no longer the clearly defined ultimate facts they seemed to be; we know so much, at least, that they are intimately connected with electrical phenomena, though not to what extent. That electricity is implicated with chemical composition, and recomposition, is clearly recognised; and Sir J. Herschel has lately expressed his opinion, that it is impossible any longer to attempt the explanation of the movements of all the heavenly bodies by simple attraction, as understood in the Newtonian theory—these comets, with their trains perversely turned from the sun, deranging sadly our systematic views. The ray of light, which, with its reflection and its refraction, seemed a quite manageable substance, has deserted us, and we have an ethereal fluid—the same as that which constitutes heat, or another—substituted in its stead. Science has no language, and knows not how to speak. If she lectures one day upon the "polarisation" of light, she professes the next not to know what she means by the term; she is driven even to talk of "invisible rays" of light, or chemical rays. Never was it so difficult to form any scientific conception on these subjects, or to speak of them with any consistency. Mrs Somerville is a correct writer; yet she opens her brief section upon magnetism thus:—"Magnetism is one of those unseen imponderable existences, which, like electricity and heat, are known only by their effects. It is certainly identical with electricity, for," &c. It is like, and it is identical, in almost the same sentence.
Even in the fields of astronomy, where we have to deal with large masses of matter, it is no longer possible for the imagination to form any embraceable system. We are plunged into hopeless infinitude, and the little regularities we had painfully delineated on the heavens are all effaced. The earth had been torn from its moorings and sent revolving through space, but it revolved round a central stationary sun. Here, at least, was something stable. The sun was a fixed centre for our minds, as well as for the planetary system. But the sun himself has been uprooted, and revolves round some other centre—we know not what—or else travels on through infinite space—we know not whither. A little time ago, the stately seven rolled round their central orb in clear and uninterrupted space; their number has been constantly increasing; we reckon now seventeen planetary bodies that can be reduced to no law of proportion or harmony, either as to their size, their orbits, the inclination of their axes, or any other planetary property;[15] and the space they circulate in is intruded on by other smaller and miscellaneous bodies, asteroids, and the like, some of which, it seems, occasionally fall to the earth. Comets come sweeping in from illimitable space, requiring, it is thought, some eight thousand years for their revolution round the sun. Some of these cross each other's orbits: one has crossed the orbit of the earth; and their decreasing circle round the sun, gives notice of some unknown ether suffused through the interstellar spaces. The outlying prospect, beyond our system, grows still more bewildering. The stars are no longer "fixed," nor is their brilliancy secured to them; this increases and diminishes with perplexing mystery. What seemed a single point of light, resolves itself into two stars revolving round each, perhaps reciprocally sun and planet. The faint and telescopic nebula, just reached by the glass in one age, is found in the next to be a congregation of innumerable stars. Our milky way is, at the same distance, just such another nebula. "The elder Herschel calculates that the light of the most distant nebula, discovered by his forty-feet refractor, requires two millions of years to reach our eyes." Oh, shut up the telescope! the reason reels.
Science, in short, presents before us a field of perpetual activity—of endless excitement, and that of the highest order—of practical results of the greatest utility and most beneficial description; but it gives no prospect of any resting-place—any repose for the speculative reason—any position with which the scientific mind shall be content, and from which it shall embrace the scene before it in its unity and harmony. Always will it be
"Moving about in worlds half-realised."
Having touched upon these subtle agencies of light, and heat, and electricity, and on the increasing difficulty we have of framing to ourselves any distinct conception of them, we cannot refrain from alluding to a little work or pamphlet, by Mr Grove, entitled, The Correlation of Physical Forces, in which this subject is treated with great originality. Mr Grove has made himself a name in experimental science by his discoveries in electricity and chemistry; in this pamphlet he shows, that he has the taste and power for enlarged speculation on the truths which experiment brings to light. We would recommend the perusal of his pamphlet to all who are interested in these higher and more abstract speculations. How far the wide generalisation he adopts is sustained by facts, we are not prepared to say. But it is a powerful work, and it is a singular one; for it is not often, in this country at least, that a man so well versed in the minutiæ of science ventures upon so bold a style of generalisation. After reviewing some of the more lately discovered properties of electricity, heat, light, and magnetism, and showing how each of them is capable of producing or resolving itself into the others, he reasons that all the four are but the varied activity of one and the same element. He adds, that this element is probably no other than the primitive atom itself; and that, in fact, these may be all regarded as affections of matter, which follow in their legal sequence, and not as the results of separate fluids or ethers. We are not sure that we do justice to his views, as we have not the work at hand, and it is some time since we read it; but we are persuaded that its perusal will be of interest to a philosophic reader, though its reasoning should fail to satisfy him.