 More specifically, God is identical with one of the two ungenerated and indestructible first principles (archai) of the universe. One principle is matter which they regard as utterly unqualified and inert. It is that which is acted upon. God is identified with an eternal reason (logos, Diog. Laert. 44B ) or intelligent designing fire or a breath (pneuma) which structures matter in accordance with Its plan (Aetius, 46A). The designing fire is likened to sperm or seed which contains the first principles or directions of all the things which will subsequently develop (Aristocles in Eusebius, 46G). The biological conception of God as a kind of living heat or seed from which things grow seems to be fully intended. The further identification of God with pneuma or breath may have its origins in medical theories of the Hellenistic period. See Baltzly (2003). On the entire issue of God and its relation to the cosmos in Stoicism, see the essays in Salles (2009).