We see six planets around the sun, the earth is the third; they all move in elliptical orbits; they have all a rotatory motion like the earth, as well as spots, irregularities, mountains: some of them have satellites, the earth has one satellite: Jupiter is flattened like our world; in short there is every possible resemblance between the planets and the earth: is it, then, rational to suppose the existence of living and thinking beings is confined to the earth? From what is such a privilege derived but the groveling minds of persons who can never rise above the objects of their immediate sensations? Lambert believed that even the comets were inhabited. (Systême du Monde, Bouillon; 1770.) Buffon determines the period when each planet became habitable, and when it will cease to be so, from its refrigeration. (Suplèmens, in 4to. tom. 11.) What I have said of planets that turn round the sun, will naturally extend to all the planetary systems which environ the fixed stars; every star being an immoveable and luminous body, having light in itself, may properly be compared with our sun. We must conclude that if our sun serves to attract and enlighten the planets which surround it, the fixed stars have the same use. It is thought that the sun and fixed stars are uninhabitable because they are composed of fire; yet M. Knight, in a work written to explain all the phœnomena of nature, by attraction and repulsion, endeavours to prove that the sun and stars may be habitable worlds, and that the people in them may possibly suffer from extreme cold. M. Herschel likewise thinks the sun is inhabited (Philos. Trans. 179. p. 155, et suiv.) Some timid, superstitious writers have reprobated this system, as contrary to religion: they little knew how to promote the glory of their Creator. If the immensity of his works announce his power, can any idea be more calculated than this to exhibit their magnificence and sublimity? We see with the naked eye, several thousands of stars; in every part of the firmament we discover with telescopes, innumerable others; with more perfect telescopes, we still find a multitude more. We compute, from the number seen through Herschel's telescopes in one region of the sky, that there are a hundred millions. Imagination pierces beyond the extent of vision, beholding multitudes of unknown worlds, infinitely more in number than those which are visible to our sight; and ranges unrestrained in the boundless space of creation. Our only difficulty with respect to the inhabitants of so many millions of planets, is the obscurity of the final causes, which it is difficult to admit when we see into what errors the greatest philosophers have fallen; for instance Fermat, Leibnitz, Maupertius, &c. in attempting to employ these final causes or metaphysical suppositions of imagined relations between effects that we see and the causes we assign them, or the ends for which we believe them to exist.