Ancient philosophy of nature (phusis) is a study of not only physical things but also the metaphysical entities and doctrines that most directly condition the study of natural things. Hence, for instance, philosophy of time, regardless of our expectations, falls within this study. Neoplatonist natural philosophy rests on an intellectual background that is partly Aristotelian and partly Platonic. First, Neoplatonists build on and react to the Aristotelian idea of nature and the soul’s role in it. Nature refers to the forms of the sensibles
that exist by nature, as distinct, for instance, from artefacts. ese are things that change naturally, that is, that have an internal principle of change and stability in them, as opposed to whatever needs to be changed from outside, externally (Arist. Ph. 2.3, 192b13-14, 20-23; Metaph. Δ 4, 1014b16-1015a19). A particular feature of the Neoplatonic conception of nature lies in the idea that despite the appeal to an internal principle of life, nature is not autonomous but organized and maintained by higher, intelligible principles. Crucial intermediaries here are the immanent logoi, or rational forming principles, in matter, which owe their power and intelligibility to the higher principles: to Forms. e late Neoplatonist Simplicius states against Aristotle that if the seed did not include such a relation to the higher principles, it would only be capable of giving rise to another seed (Simpl. in Phys. 312,18-314,15 [= Sorabji 2004: 1 (b) 8]). In his view, the fact that the e ects in nature may re ect features that are in no way apparent in the causes is a testimony to the involvement of non-immanent principles.