The subject I have in mind is but a trifle—namely, the question whether there is or is not a God; and I am going to examine it in all seriousness and good faith, because it interests me, and you also.
I
OF THE PRINCIPLE OF ACTION
Everything is in motion, everything acts and reacts, in nature.
Our sun turns on its axis with a rapidity that astonishes us; other suns turn with the same speed, while countless swarms of planets revolve round them in their orbits, and the blood circulates more than twenty times an hour in the lowliest of our animals.
A straw that is borne on the wind tends naturally towards the centre of the earth, just as the earth gravitates towards the sun, and the sun towards the earth. The sea owes to the same laws its eternal ebb and flow. In virtue of the same laws the vapours which form our atmosphere rise continually from the earth, and fall again in dew, rain, hail, snow, and thunder. Everything, even death, is active. Corpses are decomposed, transformed into plants, and nourish the living, which in their turn are the food of others. What is the principle of this universal activity?
This principle must be unique. The unvarying uniformity of the laws which control the march of the heavenly bodies, the movements of our globe, every species and genus of animal, plant, and mineral, indicates that there is one mover. If there were two, they would either differ, or be opposed to each other, or like each other. If they were different, there would be no harmony; if opposed, things would destroy each other; if like, it would be as if there were only one—a twofold employment.
I am encouraged in this belief that there can be but one principle, one single mover, when I observe the constant and uniform laws of the whole of nature.
The same gravitation reaches every globe, and causes them to tend towards each other in direct proportion, not to their surfaces, which might be the effect of an impelling fluid, but to their masses.
The square of the revolution of every planet is as the cube of its distance from the sun (which proves, one may note, what Plato had somehow divined, that the world is the work of the eternal geometrician).
The rays of light are reflected and refracted from end to end of the universe. All the truths of mathematics must be the same on the star Sirius as in our little home.