This paper surveys the meaning of aither in Empedocles. Since Aristotle, Empedoclean aither has been generally considered synonymous with air and understood anachronistically in terms of its Aristotelian conception as hot and wet. In critiquing this interpretation, the paper first examines the meaning of “air” in Empedocles, revealing scant and insignificant use of the term. Next, the ancient controversy of Empedocles’ “four roots” is recast from the perspective that aither, rather than air, designates the fourth root. Finally, the nineteen instances (...) of aither in Empedocles’ fragments are considered, revealing a bright and energetic root closely related to the force of life. (shrink)