Holding this view of the elements, the Stoics, it will be seen, did not deviate to any very great extent, in their ideas of the World, from Aristotle and the views which were generally entertained. In the centre of the Universe reposes the globe of the earth; [464] around it is water, above the water is air. These three strata form the kernel of the world, which is in a state of repose, [465] and around these the Ether revolves in a circle, together with the stars which are set therein. At the top, in one stratum, are all the fixed stars; under the stratum containing the fixed stars are the planets, in seven different strata—Saturn, Jupiter, Mars, Mercury, Venus, then the Sun, and in the lowest stratum, bordering on the region of air, is the Moon. [466] Thus the world consists, as with Aristotle, of a globe containing many strata, one above another. [467] That it cannot be unlimited, as Democritus and Epicurus maintain, follows from the very nature of body. [468] The space within the world is fully occupied by the material of the world, without a vacant space being anywhere left. [469] Outside the world, however, is empty space, or else how—the Stoics asked—would there be a place into which the world could be resolved at the general conflagration? [470] Moreover, this empty space must be unlimited; for how can there be a limit, or any kind of boundary, to that which is immaterial and non-existent? [471] But although the world is in empty space, it does not move, for the half of its component elements being heavy, and the other half light, as a whole it is neither heavy nor light. [472] [(1) Stars.] The stars are spherical masses, [473] consisting of fire; but the fire is not in all cases equally pure, [474] and is sustained, as Heraclitus taught, by evaporations from the earth and from water. [475] With this process of sustentation the motion of the stars is brought into connection, their orbit extending over the space in which they obtain their nutriment. [476] Not only the sun, but the moon also, was believed to be larger than the earth. [477] Plato and Aristotle had already held that the stars are living rational divine beings; and the same view was entertained by the Stoics, not only because of the wonderful regularity of their motion and orbits, but also from the very nature of the material of which they consist. [478] The earth, likewise, is filled by an animating soul; or else how could it supply plants with animation, and afford nutriment to the stars? [479] Upon the oneness of the soul, which permeates all its parts, depends, in the opinion of the Stoics, the oneness of the universe. [(2) Meteorology.]