It depends on who you ask. Hesiod thought Gaia was first so I guess he would say Earth. Heraclitus picked Fire as the first principal. Thales liked Water. Anaxamander went with Air which in his view was rarified to make fire, condensed to make water and earth. No one agreed. Empedocles, one of the Atomists, regarded the elements as equally eternal; Philistion his pupil equated the elements with four qualities, Air-Cold, Fire-Hot, Water-Moist, Earth-Dry. Personaly I think of Air-Dry and Earth-Cold. Aristotle thought different from both of us and assigned two qualities to each element instead. Ptolemy came along in his Tetrabiblos and assigned the directions to the qualities as: East- Dry, South- Hot, West- Moist, North- Cold. 1800 years later the Golden Dawn (which we know had read the Neoplatonists and Ptolemy) and other occult circles started calling the quarters. Might have happened in small groups earlier, we will never know for sure, but from there entered into the then nascent Pagan movement from there in the early 1900's. For me the Four Elements is a convenient way of thinking about and relating to the earth. They do represent the basic foundation of life as we know quite well. We need food grown in the earth or harvested from the sea, we need water, we need breath, we need warmth. Starhawk calls them the Four Sacred Things: http://www.cyberus.ca/~sustain1/solution/Commitment.shtml Works for me.