217. The æther is therefore not absolutely imponderable, but only so in relation to the heavenly bodies. Light and heat are therefore ponderose substances, though they are not ponderable.
218. The separation of the æther into central and peripheric mass has happened according to the laws of light, and thus according to the centroperipheric primary antagonism. As a consequence of this, only one central body can originate in a solar system; the mass of the periphery can, however, divide into several, and must divide into as many as the light has moments of operation; of this we shall speak for the first time in treating of colours.
219. The matter of the periphery can be condensed by light into no other form than that of a hollow globe around the sun. The planets are originally concentric hollow globes, in the midst of which the sun is formed. There are several hollow globes, because the light has several points of contraction at certain distances from the sun.
220. The number of hollow planetary globes is a definite one, and it is not an arbitrary matter how many of them originate.
221. The matter of such a hollow globe of æther is still, however, rarer by so much than the present planetary mass, as that of our earth would be rarer if it were to form a hollow globe around the sun, about as thick only as from the earth to the moon.
222. This hollow globe rotates with the sun, because the whole globe of æther, which fills out the space of the subsequent solar system, rotates; therefore everything necessarily tends in one direction.
223. These hollow planetary globes, on account of the rarity of their mass, their rotation, and the greater tension of light, could not subsist in the equatorial plane of the solar system, but coagulate together in equatorial rings about the centre of the whole system. The planetary fœtuses are only solar rings, which rotate with the sun.
224. If the whole coagulated æther of the solar system be so small in quantity, that when extended around the sun in a planetary track or course, it still does not become solid; so also can the orbitar ring not persist, but it contracts itself through light, rotation and the peculiar excited gravity into a globe. This globe continues to rotate, as it did when under the conditions of orbitar ring, of hollow globe and as æther; i. e. it pursues a course around the sun. The peripheric globe travels necessarily in the same plane in which the sun rotates. This is therefore called the zodiac. This globe rotates also around its own axis and virtually in the same direction, according to which it performs its course or the sun rotates. A globe coursing and rotating around the sun in its equatorial plane and in its direction is called planet.
225. At the first aggregation of the mass of the planetary ring into a planetary globe, the latter was still very much extended, the earth extending beyond the moon. The mass was thus gaseous. What happened in the great globe of æther, of which the sun has become the centre, happens also here. An opposition of centre to periphery again originates; and a subordinate sun and new orbitar rings are formed. If the mass of the planetary equatorial ring be only small and consequently rare, it rolls into a globe and together with this into moons.
226. If it be much, consequently so dense, that it coheres, it remains stationary, and is Saturn's ring.