If we are now to give some further idea of what these Physics are, we may say that the Stoics distinguish in the corporeal—although nature is only the manifestation of one common law—the moment of activity and that of passivity; the former is, according to Aristotle, active reason, or, according to Spinoza, _natura naturans_; the latter passive reason, or _natura naturata_. The latter is matter, substance without quality, for quality is, generally speaking, form, _i.e._ that which forms universal matter into something particular. This is indeed the reason likewise that with the Greeks quality is called τὸ ποιόν, just as we in German derive _Beschaffenheit_ from _Schaffen_—that which is posited, the negative moment. But the actuating, as the totality of forms, is, according to the Stoics, the Notion in matter; and this is God. (Diog. Laërt. VII. 134.) As regards the further nature of these forms, these universal laws of nature, and the formation of the world, the Stoics have in the main adopted the ideas of Heraclitus, for Zeno studied him very particularly (_supra_, p. 239). They thus make fire the real Notion, the active principle which passes into the other elements as its forms. The world arises by the self-existent gods driving the universal material substance (οὐσίαν) out of the fire, through the air, into the water; and as in all generation the moisture which surrounds a seed comes first as the begetter of all that is particular, so that conception, which in this respect is called seed-containing (σπερματικός), remains in the water and then actuates the indeterminate Being of matter into the origination of the other determinations. The elements, fire, water, air and earth, are consequently primary. Respecting them the Stoics speak in a manner which has no longer any philosophic interest. “The coagulation of the denser parts of the world forms the earth; the thinner portion becomes air, and if this becomes more and more rarefied, it produces fire. From the combination of these elements are produced plants, animals, and other kinds of things.” The thinking soul is, according to them, of a similar fiery nature, and all human souls, the animal principle of life, and also plants, are parts of the universal world-soul, of the universal fire; and this central point is that which rules and impels. Or, as it is put, souls are a fiery breath. Sight, in the same way, is a breath of the ruling body (ἡγεμονικοῦ) transmitted to the eyes; similarly hearing is an extended, penetrating breath, sent from the ruling body to the ears.[128]