Nature makes nothing incomplete, and nothing in vain.

This line reflects Aristotle’s teleological view of nature: natural processes are intelligible in terms of ends (telē) and functions. Across his biological works and the Physics, Aristotle argues that organs, capacities, and regular natural developments are best explained by what they are “for,” rather than by chance alone. The maxim is often cited in discussions of his natural philosophy and biology, where he contrasts purposive explanation with accounts that reduce order to accident. In that framework, “nature” (physis) is not a conscious designer but an internal principle of motion and development that tends toward characteristic completions (e.g., an acorn toward an oak).

The saying asserts that nature is not wasteful: features of living things and regular natural patterns are understood as serving some role in the organism or in the unfolding of a natural kind. “Nothing incomplete” suggests that natural development aims at a finished form appropriate to the thing’s essence; “nothing in vain” denies that persistent natural structures are mere leftovers without function. Philosophically, it encapsulates Aristotle’s preference for final-cause explanations—asking what something is for—alongside material and efficient causes. It has been influential (and contested) in later debates about purpose in biology, from medieval natural theology to modern arguments over teleology and adaptation.