animals and plants, and also the earth itself, as a principle of cohesion. The world, they say, is one and finite, having a spherical shape, such a shape being the most suitable for motion, as Posidonius says in the fifth book of his Physical Discourse and the disciples of Antipater in their works on the Cosmos. Outside of the world is (Mused the infinite void, which is incorporeal. By incorporeal is meant that which, though capable of being occupied by body, is not so occupied. The world has no empty space within it, but forms one united whole. This is a necessary result of the sympathy and tension which binds together things in heaven and earth. Chrysippus discusses the void in his work On Void and in the first book of his Physical Sciences ; so too Apollophanes in his Physics, Apollodorus, and Posidonius in his Physical Discourse, book ii. But these, it is added [i.e. sympathy and tension], are likewise bodies. Time too is incorporeal, being the measure of the world's motion. And time past and time future are infinite, but time present is finite. They hold that the world must come to an end, inasmuch as it had a beginning, on the analogy of those things which are understood by the senses. And that of which the parts are perishable is perishable as a whole. Now the parts of the world are perishable, seeing that they are transformed one into the other. Therefore the world itself is doomed to perish. Moreover, anything is destructible if it admits of deterioration ; therefore the world is so, for it is first evaporated and again dissolved into water.