Air (and its variant spellings eir, eyr, aier, ayre, eyir, eire, eyer, ayer, aire, ayere, and ayr) all stem from the Latin aer. It is the most transparent but immediately necessary of all the classical Greek elements. It surrounds the Earth as atmosphere and was considered a mediating element, somewhere between fire and water, both warm and moist, the driving force behind the birth of the cosmos. As a spiritual element it pushed along the soul—the Greek work for spirit, pneuma, also means breath—and spread messages and ideas across the world in its guise as wind. In the early twenty first century, as gas, air represents one of the fundamental states of matter (the others being solid and liquid), while its pollution by technological activities constitutes a fundamental ethical challenge.

Air in Science

Air figures prominently in both physics and chemistry, and as atmosphere is subject...