Now, it is evident that if you undertake to express the distance of sun from planet in terms of the time, at this rate of velocity, it is reduced to nothing. The sun is as effectually present, for instance, in his all-important gravitating influence, at every instant of time, in the planet Neptune, nearly three thousand millions of miles away, as the hand of the schoolboy is present at the end of his sling, while he whirls it round his head, and retains the stone in its place by the string. Cut the string, and the stone flies off; suspend for an instant the influence, or force, or attraction, or whatever you please to call it, which binds Neptune to the sun, and he flies off in a path more eccentric than any comet's.
There are two ways of spanning distance: one by actual, bodily transit; another by the transmission of an impulse or wave, propagated and repeated along the space intervening, in some medium more or less mobile or subtle. The planetary motions are good examples of the actual translation of bodies through space: this earth of ours sweeping along, in its orbit round the sun, at a rate of something like nineteen miles in a second, or 68,000 miles in an hour, besides its rotatory motion on its axis of 24,000 miles every day. The planet Venus exceeds this velocity, travelling at the rate of 80,000 miles an hour; while Mercury, in the same time, accomplishes 109,360 miles. Even this inconceivable velocity is far surpassed by the comet of 1843, which, with a tail two millions of miles long, and a nucleus apparently larger than our globe, swept round the sun, at its perihelion, at the rate of 366 miles, or nearly the distance from Edinburgh to London, in one second. [Footnote 132]
[Footnote 132: Outline of Astronomy, §590, 593.]
Velocities of impulse exceed those of bodily translation; that is, supposing we may class among examples of wave motion the transmission of sound, light, electricity, and perhaps gravitation. Dr. Lardner mentions his having, on one occasion, in company with Leverrier, written a message by electric telegraph, at a distance of more than a thousand miles, and at the rate of 19,500 words in an hour, or of 5.5 words in a second. [Footnote 133] At a similar distance, and indeed at a much greater, a steel bar may be made to vibrate fourteen thousand miles in a second. [Footnote 134] Such a velocity evidently far surpasses the power of human comprehension. Even in regard to the less rapid transmission of light, the eminent astronomer Bessel candidly confesses that "the distance which light traverses in a year is not more appreciable to us, than the distance which it traverses in ten years. Therefore, every endeavor must fail to convey to the mind any idea of a magnitude exceeding what is accessible on the earth." [Footnote 135]
[Footnote 133: Museum of Science and Art, part viii. p. 116.]
[Footnote 134: Ib., Part ix. p. 201.]
[Footnote 135: Quoted, Cosmos, iii. 85.]
Now, even supposing that we are acquainted with all the methods which exist in nature for spanning vast distances, and if, as we have shown, distance may be expressed in terms of the time taken to travel over it, or transmit a communication across it, the thought forcibly occurs. What is distance, if viewed apart from the means at disposal for overpassing it? A friend in the next room is not nearer us than another in the next continent, if in the same interval of time we can communicate with either. To be sure, one of them we might see sooner than the other, but sight is no necessary means of communicating; the blind are forever debarred from it. Man can communicate with man, even materially, without either sight or hearing; and far beyond the range of either.
But who shall be bold enough to say that other and subtler methods of communication may not exist in the material universe? or that the world of spirit has none more vivid than those subtle currents which permeate the world of matter? To a generation or two ago, the means of transmitting intelligence, which are now quite familiar to us, would have seemed fabulous; a little further back in the history of Europe, their discovery might have involved the penalty due to witchcraft. If the passage of a material impulse across the wide orbit of Neptune unites him intimately at every moment with the sun, is there any distance that can be said absolutely to present an impassable gulf to the intercourse of spirit with spirit? Or, can it be said that some such means of communication do not, and cannot exist, because human senses do not perceive them, nor human intelligence comprehend them? Transmission by impulse surpasses in velocity every known instance of actual, bodily translation: why must what we yet know of the former be fixed as the limit of what is possible? Why may there not be some means of communication surpassing in swiftness the flash of the lightning, or the influence of gravitation, as far as it exceeds the sweep of the comet or the slow progress of the pedestrian? Why must it be pronounced an idle dream, that we may hold one end of a chain of impulses vibrating from earth to heaven, lying along the future track of our emancipated and purified spirits?
And pursuing analogy one step further, it is no severe demand on the imagination to conceive that the universal presence of God, which embraces and interpenetrates the immensity of space, may be, to the subtle and vivid impulses from spirit to spirit, what, in another order of things, the elastic ether of the planetary and sidereal spaces is to vibrations of material creation; that it may fulfil for those similar functions of propagation and transmission. In him who is everywhere, at every instant, and forever, intelligence may easily be conceived to pass between the remotest points of space, with a speed not slower than coexistence itself; for any him there is no passage or motion either in time or space; he is the one indivisible Eternal, here and now.
V.
We are forcibly struck, while referring to the discoveries of modern science, with the very slender ground on which the mass even of educated persons accept their most astonishing and improbable results. How many persons of all those who talk, with much fluency and show of knowledge on subjects of physical science, have tested, by their own observation, the truth of one of the phenomena which they converse about? How many persons, for instance, who tell us that light and heat in the same ray have been separated, have actually proved it by personal experiment, or even seen it proved by another? How many persons are there at this moment in England and Scotland who have verified by their own observation and calculation the size and figure of the earth, or its distance from the sun and moon; not to mention other more intricate problems in physics, of which they have no personal knowledge whatever? The mass of mankind are content to receive these things on sufficient testimony of men competent, or whom they deem competent, to inform them on such subjects. Here, at least, in the domain of science, there is no exaltation of private judgment, no rebellion against scientific authority; and it is a wise and a just arrangement that it should be so. There are not many men, in any age, furnished with the intellectual outfit necessary for such verifications; a lifetime would not be sufficient to enable one man to accomplish them all. Sir John Herschel has the following admirable remarks, which are very much to our present purpose. "What mere assertion will make any one believe, that in one second of time, in one beat of a pendulum of a clock, a ray of light travels over 192,000 Miles, and would therefore perform the tour [{383}] of the world in about the same time that it requires to wink with our eyelids, and in much less than a Swift runner occupies in taking a single stride? What mortal can be made to believe, without demonstration, that the sun is almost a million times larger than the earth? and that, although so remote from us that a cannon ball shot directly toward it would be twenty years in reaching it, yet it affects the earth by its attraction in an appreciable instant of time? But what are these to the astonishing truths which modern optical inquiries have disclosed, which teach us that every point of a medium through which a ray of light passes is affected with a succession of periodical movements, regularly occurring at equal intervals, no less than five hunted millions of millions of times in a single second? That it is by such movements, communicated to the nerves of our eyes, that we see; nay, more, that it is the frequency of their recurrence which affects us with the sense of the diversity of color. That, for instance, in acquiring the sensation of redness, our eyes are affected four hundred and eighty-two millions of millions of times; of yellowness, five hundred and forty-two millions of millions of times; and of violet, seven hundred and seven millions of millions of times in a second. These are nevertheless, conclusions to which any one may most certainly arrive, who will only be at the trouble of examining the chain of reasoning by which they have been obtained."