physis

Physis is a Greek term commonly translated as nature or the physical world. In ancient Greek thought, physis referred to the inherent character and autonomous processes of things as they come to be, in contrast with human artifice, law, or convention. The word is central to the tradition of natural philosophy, the precursor to modern science, and it is the linguistic root of many scientific terms.

Etymology and scope: Physis derives from a root associated with growth or emergence. In English, it gave rise to physics and physical, and in compounds to physiology and other fields, all linking to nature or natural processes.

Philosophical usage: In pre-Socratic philosophy, thinkers sought to explain physis as the ultimate principle of reality. Thales identified the physis as water or as a unified principle, while Heraclitus emphasized change as a feature of physis. Aristotle defined physis as the internal principle of motion and rest in natural objects; for him, natural things grow and strive toward their ends by their internal form and teleology (entelechy).

Later usage: In medieval and early modern philosophy, physis was contrasted with nomos (law, convention) and with techne (art). The term helped frame debates about nature, causation, and the laws governing the physical world. With the rise of modern science, “natural philosophy” gradually became “physics” as a distinct discipline; the root remains visible in terms such as physical and physiology.

See also: physics, philosophy of nature, natural philosophy.