=186.= Having fully considered bodies and their relationships, we proceed to consider their combination. In ordinary experience we meet with three kinds of combination; juxtaposition (παράθεσις), as in a mixture of various kinds of grain; mixture (μῖξις), when solid bodies are interfused, as fire and heat, or fusion (κρᾶσις), when fluids are interfused, as wine poured into the sea; chemical mixture (σύγχυσις), when each of the two bodies fused disappears[78]. Of these the second in its most completed form (κρᾶσις δι’ ὅλων, _universa fusio_) is of high importance. For in this way we find that soul is fused with body[79], quality with substance[80], light with air[81], God with the universe[82]. Aristotle admits that there is this mixture between substance and qualities; but as both of these are to the Stoics bodies, and so too are the members of the other pairs quoted, the Stoic doctrine must be summed up in the paradox ‘body moves through body[83].’ This also follows from the Stoic doctrine that there is no void in the universe. Correspondingly the sum total of body in its various aspects and mixtures completes the whole (ὅλον), which is identical with the ‘world-order’ or ‘universe’ (κόσμος)[84]. It seems likely that this important conception had been reached in very early times by the Chaldaean astronomers; it was definitely propounded by Pythagoras[85], had been taken up by Socrates[86] and the Sophists[87], and was in Stoic times generally accepted both in popular philosophy and in scientific investigation. [Sidenote: Quiddities.] =187.= Up to this point the Stoic system has been guided by a determined monism. Body is; that which is not body is not. Yet in the end the Stoics feel compelled to speak of certain things which are not body (ἀσώματα, _incorporalia_). In the first instance there is the void beyond the universe[88]. It is possible to dispute as to whether void may more correctly be said to exist or not to exist; but at least it is a part of nature[89], and we need some term like ‘the all’ (τὸ πᾶν) to include both the universe and the void beyond[90]. Next we have to deal with statements (λεκτά), and mental conceptions of every kind, which stand as a class in contrast with the real objects to which they may or may not respectively correspond[91]. Lastly, the Stoics included space and time, which they had previously explained as functions of body, in the list of things not bodily[92]. Having thus reached the two main classes of ‘bodies,’ and ‘things not bodily,’ the monistic principle can only be saved by creating a supreme class to include both. Let this then be called the existent (τὸ ὄν, _quod est_)[93], or, if it be objected that things incorporeal do not exist[94], we may use the name ‘quiddities’ (τινά, _quid_)[95]. In this way the monistic theory, though a little damaged in vitality, is again set on its feet so far as the ingenious use of words can help. [Sidenote: Statements.]