Physis

Physis (φύσις), the Greek word we translate 'nature', comes from the verb phyō / phyesthai, 'to grow, to bring forth, to spring up'. At root it names not a static collection of things but a process — the growing, the coming-to-be and unfolding of a thing from within — and then, by extension, the settled character or constitution a thing has by virtue of how it grows. The Latin natura, from nasci ('to be born'), translates it well, carrying the same image of birth and growth.

Physis was the great theme of the earliest philosophers: so many of them wrote works that later bore the title Peri Physeōs, 'On Nature', that the term came to define the whole first age of Greek thought, the inquiry into the archē and origin of the natural world. To ask after the physis of a thing was to ask what it truly and originally is, beneath appearances.

Nature against convention

In the hands of the fifth-century Sophists physis became one pole of a famous and explosive antithesis: physis against nomos, nature against custom or law. Is justice rooted in the nature of things, or is it merely a convention imposed by societies and varying from place to place? Are the distinctions among human beings natural or merely customary? This debate, which runs all through Plato's dialogues, set the terms for political and ethical philosophy ever after.

For the Neoplatonists, Physis took on a more exalted role as the lowest power of the World Soul — the immanent, half-conscious force that, working from within, shapes living things and clothes the formative principles (logoi) of Intellect in the matter of the visible world.