=193.= The phenomena of earth and heaven combined, in the general opinion of intelligent men, to show the existence of a ‘world-order’ or ‘universe[10].’ The Stoics accepted this conception in their physics from Heraclitus, who had declared that ‘neither god nor man created this world-order,’ as in their ethics from Diogenes, the ‘citizen of the universe[11].’ They therefore needed only to adjust an established notion to their own physical postulates. We observe at once that the very conception of an ordered whole differentiates that whole from the absolute totality of all things. The universe is indeed on the one hand identified with the substance of all things (οὐσία τῶν ὅλων), but only as a thing made individual by the possession of quality (ἰδίως ποιόν)[12], and necessarily one[13]. It is self-created; and it may therefore be identified with its creator, the deity[14]; it also includes all that is bodily[15]; but outside there remains the boundless void[16]. It is therefore defined by Chrysippus as ‘the combination of heaven and earth and all natures that are in them,’ or alternatively as ‘the combination of gods and men and all that is created for their sake[17].’ [Sidenote: Its position.] =194.= The Stoic conception of the universe is therefore that of a continuous body, having a definite outline, and stationed in the boundless void. That the universe has shape the Stoics deduce from its having ‘nature’ (φύσις), that is, the principle of growth, displayed in the symmetry of its parts[18]; and its shape is the perfect shape of a sphere[19]. Within this sphere all things tend towards the middle[20]; and we use the terms ‘down’ meaning ‘towards the middle,’ and ‘up’ meaning thereby from the middle[21]. The Peripatetics are therefore needlessly alarmed, when they tell us that our universe will fall down, if it stands in the void; for, first, there is no ‘up’ or ‘down’ outside the universe; and, secondly, the universe possesses ‘unity’ (ἕξις)[22] which keeps it together[23]. And here we see the folly of Epicurus, who says that the atoms move downwards from eternity in the boundless void; for there is no such thing as ‘downwards’ in that which is unlimited[24]. Further, the universe is divided into two parts, the earth (with the water and the air surrounding it) which is stable in the middle, and the sky or aether which revolves around it[25]. [Sidenote: The heliocentric theory.]