PLANETS, nature of the. That the plan ets are opaque bodies, like our. Earth, ap pears evident for the following reasons : 1. Since in Venus, Mercury, and Mars, only that part of the disc illuminated by the Sun is found to shine ; and again, Venus and Mercury, when between the Earth and the Sun, appear like dark spots, or macula, on the Sun's disc ; it is evident that Mars, Venus, and Mercu ry, are opaque bodies, illuminated with the borrowed light of the Sun. And the same appears of Jupiter, froln its being void of light in that part to which the shadow of the satellites reaches, as well as in that part turned from the Sun ; and that his satellites are opaque, and reflect the Sun's light, is abundantly shown. Wherefore, since Saturn, with his ring and satellites, only yield a faint light, fainter considerably than that of the fixed stars, though these be vastly more re mote, and than that of the rest of the planets, it is past doubt, he too, with his attendants, are opaque bodies. 2. Since the Sun's light is not transmitted through Mercury and Venus, when plac ed against him, it is plain they are dense opaque bodies ; which is likewise evi dent of Jupiter, from his hiding the satel lites in his shadow ; and therefore, by analogy, the same may be concluded by Saturn. 3. From the variable spots in
Venus, Mars, and Jupiter, it is evident these planets have a changeable atmo sphere ; which changeable atmosphere may, by a like argument, be inferred of the satellites of Jupiter, and therefore by similitude the same may be concluded of the other planets. 4. In like manner, from the mountains observed in Venus, the same may be supposed in the other planets. 5. Since, then, Saturn, Jupiter, both their satellites, Mars, Venus, and Melcury, are opaque bodies, shining with the Sun's borrowed light, are fur . rushed with mountains, and encompass ed with a changeable atmosphere ; they have, of consequence, waters, seas, &c. as well as dry land, and are bodies like the Moon, and therefore like the Earth. And hence it seems highly probable, that the other planets have their animal in habitants, as well as our Earth.