_c._ He further made this fire to be a real process; because its reality is for itself the whole process, the moments have become concretely determined. Fire, as the metamorphosis of bodily things, is the transformation and exhalation of the determinate; for this process Heraclitus used a particular word—evaporation (_ἀναθυμίασις_)—but it is rather transition. Aristotle (De anim. I. 2) says of Heraclitus in this regard, that, according to his view, “the soul is the principle because it is evaporation, the origination of everything; it is what is most incorporeal and always in a state of flux.” This is quite applicable to the primary principle of Heraclitus. Furthermore he determined the real process in its abstract moments by separating two sides in it—“the way upwards (_ὁδὸς ἄνω_) and the way downwards (_ὁδὸς κάτω_)”—the one being division, in that it is the existence of opposites, and the other the unification of these existent opposites. Corresponding to these, he had, according to Diogenes (IX. 8), the further determinations “of enmity and strife (_πόλεμος_, _ἔρις_), and friendship and harmony (_ὁμολογία_, _εἰρήνη_); of these two, enmity and strife is that which is the principle of the origination of differences; but what leads to combustion is harmony and peace.” In enmity amongst men, the one sets himself up independently of the other, or is for himself and realizes himself; but unity and peace is sinking out of independence into indivisibility or non-reality. Everything is thre-fold and thereby real unity; nature is the never-resting, and the all is the transition out of the one into the other, from division into unity, and from unity into division.