It is now not merely in the larger and more obvious operations of Nature that we can trace this marvellous ubiquity of law, but in her most hidden processes and inmost constitution. At every point, we are forced to ask why things should be as they actually are, and how they came to be subject to conditions which they cannot be supposed to have created for themselves. Why, for example, should the ultimate elements of matter,—be they atoms, or electrons, or whatever else,—always and everywhere observe the same rules of the great game in which they serve as counters? Why, to take a concrete instance, should atoms of Hydrogen in Sirius, or in a star of the Milky Way, obey just the same laws as do those with which we make coal-gas or spirit of salt? These various atoms, as Lord Grimthorpe reminds us, have never been within billions of miles of one another. What is the mysterious influence which links them together across the depths of space? That they are so linked is obvious; for if we can ascertain the existence of such a substance in other spheres, it is only because the light it emits, exactly agrees when analyzed in the spectroscope with that of hydrogen flames in our own laboratories. How comes it, again, that the seventy different kinds of atoms, (to speak in round numbers)—are distributed—according to Mendeléeff's periodic law,—among some seven groups or families, the members of each group resembling one another in various particulars, wherein they differ from the rest? Or, to pass from atoms to molecules, (in which atoms of the same or[{89}] of different kinds combine, to build up simple or compound substances respectively,)—how is it that molecules of the same kind are always constructed upon exactly the same model, resembling one another far more closely than sovereigns struck from the same die, or different copies of this morning's Times? It was in this uniformity of type, character and behaviour, repeated always and everywhere, in instances multiplied "beyond the power of imagination to conceive," that Sir John Herschel[125] saw a feature stamping atoms and molecules as "manufactured articles, and subordinate agents," which, no less than a line of spinning-jennies, or a regiment of soldiers clad in the same uniform, and going through the same evolutions, imply a controlling force directing things according to a definite system.
These and innumerable other particulars of detail has Science added to the problem: but of anything which can supply an answer, she knows no more than did the first man who ever mooted the question within his own soul.
And if in the inorganic world we find food for such considerations, with immensely greater instance are they forced upon us by a study of the organic. Here we enter a new realm of mystery, for the laws we encounter actively energizing at every point, are altogether different from those with which hitherto we have had to deal. The matter which enters into the constitution of living things,—animals or[{90}] plants—is precisely the same as that of which the inorganic world is constituted. No single atom or molecule is found in the one which has not been drawn from the other;—nor when incorporated in a living structure do atoms or molecules suffer any alteration, or change their nature in any respect, for, says Clerk-Maxwell,[126] throughout all changes and catastrophes these remain "unbroken and unworn." Nevertheless, they fall at once under the spell of a force which introduces into their operations an order altogether new, for it somehow strikes across all the laws of dead matter, setting up a new code of its own, which endures just so long as life lasts, and is never met with apart from life. And these organic laws issue in marvellous results. Professor Haeckel himself, after endeavouring to show that from the inorganic world no arguments can be drawn to favour the supposition of design in Nature, thus continues:[127]
But the idea of design has a very great significance and application in the organic world. We do undeniably perceive a purpose in the structure and in the life of an organism. The plant and animal seem to be controlled by a definite design in the combination of their several parts, just as clearly as we see in the machines which man invents and constructs; as long as life continues, the functions of the several organs are directed to definite ends, just as is the operation of the various parts of a machine.
How Haeckel proceeds to argue that such appearance of purposive design is merely fallacious, we need not here stay to enquire; our present concern is to attempt to realize the evidence of law and order which the world everywhere exhibits. As we have just heard, the parts of an organism, like those of a motor-car, or a chronometer, combine their operations for the production of definite ends; the attainment of which depends in all instances upon the nicest correspondence of various details of their work. Thus, that there should be eyes capable of seeing, the laws of optics must be satisfied, reflection, refraction and the rest, just as exactly in the making of an eye as in that of a telescope. De facto they are satisfied. The eye, Mr. Darwin styles[128] "a living optical instrument as superior to one of glass as the works of the Creator[129] are to those of man." He speaks, moreover, of "all its inimitable contrivances for adjusting the focus to different distances, for admitting different amounts of light, and for the correction of spherical and chromatic aberration."[130] Therefore, however we are to account for them, the laws which govern[{92}] the production of eyes successfully solve a practical problem and satisfy laws which were in force before an animal with eyes appeared on earth.
In just the same way, the requirements of sound[{93}] are met by the structure of the ear, which Sir Henry Holland, for example,[131] judged more wonderful than that of the eye itself.
So again as to wings. They are in the first place such marvellous pieces of workmanship that as Mr. Pettigrew writes concerning one of their forms.[132] "There are few things in nature more admirably constructed than the wing of a bird, and perhaps none where design can be more readily traced." But, moreover, wings entirely different in plan, as of birds, bats, and all the varieties of insects, alike satisfy the laws of aerostatics, and successfully solve in practice the problem of flight, a problem which we are unable to solve even theoretically. "It is evident," writes Lord Grimthorpe,[133] "that nobody yet thoroughly understands the whole theory of flying, though we are seeing it continually, and have unlimited opportunities of examining all sorts of wings. The explanation that appears plausible for one kind, not only will not do for another but seems refuted by it." Yet in a multitude of different ways, the forces of Nature succeed in effecting what with all our Science we cannot shew to be possible.
And concerning not merely one portion of a creature's structure, but the whole, Professor Huxley declares:[134][{94}]
The horse is in many ways a remarkable animal; not least so in the fact that it presents us with an example of one of the most perfect pieces of machinery in the living world. In truth, among the works of human ingenuity it cannot be said that there is any locomotive so perfectly adapted to its purposes, doing so much work with so small a quantity of fuel, as this machine of Nature's manufacture—the horse.