Imágenes de páginas
PDF
EPUB

not afford that kind of evidence which results

from comparison.

Still we must remember that, although it may be possible to select but few instances, out of the numerous cases which might be supposed, as evidences of a designing agent, yet the whole of the presumption arising from this source lies on one side. There is no pretence whatever for concluding, even if we could not prove design, that design exists not. Utter absence of all knowledge upon any subject can but leave the mind in a state of indifference; a state in which the smallest probability on one side should determine the judgment in its favour, unless it were balanced or counteracted by an equal or superior probability on the other side.

These remarks are not made with the intention of diminishing the conviction, which the evidence of design arising from the structure of the material universe must excite: but that we may not be looking for greater and more conclusive evidence than the nature of the case admits and may feel that any uncertainty may arise, not from the absence of sufficient proof, but from our own inability to discover and appreciate it.

As the first instance of wise design, let us turn our attention to that force which binds

the universe together, the force of gravitation. We know not the precise nature of this force; yet we can measure it by its effects. We can ascertain the law of its variation. We can compute, with great accuracy, its influence upon the heavenly bodies, and upon the waters of the ocean. Consider now, for a moment, how this one force, acting continually upon every atom of matter in the universe, and causing it to tend towards every other atom according to a definite law, becomes the means by which life and vigour are imparted to the material world. It is this which gives stability to the most solid structures, to the most stupendous mountains. It is this which envelopes the earth with the thin veil of her atmosphere, and enables the air to support the vapours and clouds which shade and fructify her surface. It is this which causes the rain to fall upon the pastures of the wilderness, the streams to flow from the hills, and the rivers to pour into the ocean the tribute of their waters. A modification of this force renders the waters buoyant, and makes the sea a pathway for the commerce of the nations which it divides. By this force also, the waters of the rivers are periodically driven backwards towards their sources, and again resume their original course; yielding to an undulation which assists the art and labour of mankind, and re

freshes crowded cities with the salubrious coolness of its accompanying breeze. The same force guides the moon in her unerring course through the heavens; directs all the planets with their train of smaller globes; and extends, probably, through the universe, further than the most distant observations can reach, uniting and compacting the whole in one entire and connected plan.

Some of these effects are apparently independent of the particular law, by which this force of gravitation varies at different distances. But, as is well known, its law is such, that every material atom is urged towards every other material atom with a force, which diminishes in the same proportion as the square of the distance increases. And in the choice of this particular law, as there is room for design, so we find reason to admire the wisdom with which the selection has been made.

It has, indeed, been attempted to exclude the notion of choice from this law, by representing it as the necessary condition of every force which tends to a center. But whoever examines without prejudice the various hypotheses which have been framed with this intention, will agree that all attempts to prove the necessary connec-.

La Place Exposition du Systême du Monde, Liv. IV. ch. xvii. p. 312. edit. 4. See also Gregory's Astronomy, and Robison's Elements of Mech. Phil. vol. I. §. 741.

tion, between the fact of a force tending to a center and its law of variation, have totally failed. Experience indeed appears sufficiently to controvert this theory; for many phenomena in the attraction and repulsion of small particles cannot be explained, except by the variation of a force in a much higher inverse ratio. It is true that the density of particles diffused from a center will diminish as the square of the distance increases: but besides the difficulty of comprehending how the divergence of particles from a center can ever cause a force which tends in the opposite direction, there is no sufficient ground for extending this law of variation to a force which is directed to a center.

There being, then, room for choice in the selection of a peculiar law, by which every atom in the universe should act upon every other atom so as to produce the regulated motions of immense masses, and yet guard. against all disorder arising from their mutual action, observe with what wisdom the existing law of nature is selected.

In that law of gravitation two things are remarkable. First, that if spheres of determinate magnitude be composed of elementary atoms, each of which attracts each with a force varying inversely as the square of the distance, these spheres attract one another with forces which

tend to their respective centers and vary in the same law. Secondly, that the mutual effect of any number of smaller bodies, revolving about a much larger central body, is such as to occasion only slight deviations from those which would take place, if the smaller bodies did not influence one another's motions: and that all variations which would endanger the stability of the system are periodical. They increase only to a certain small extent, and then diminish by the same degrees. These two conditions would have been ensured by no other law of variation in the force of gravity.

The first condition, that spheres should attract each other with a force varying in the same law as that by which the elementary particles attracted each other, would it is true have existed, on two suppositions: either that the force increased in the same proportion as the distance increased; or that the force of each particle consisted of two parts: the one increasing in the same proportion as the distance increased, and the other diminishing in the same proportion as the square of the distance increased. But neither of these suppositions would have been consistent with the second condition, by which all danger of derangement, arising from the mutual action of several bodies, is removed.

« AnteriorContinuar »