Empedocles, a fifth century BCE Greek philosopher, originated the terms Fire, Earth, Air, and Water.  He explained the nature of the universe as an interaction of two opposing principles, called love and strife, manipulating the four elements.  He stated that these four elements were all equal, all of the same age, that each rules its own province, and each posseses its own individual character.  Different mixtures of these elements produced the different natures of things.

The ancients used the term Air to graphically represent the concept of creative mentality, intellect, abstract ideas and higher human thought.   The element Air is the only one consistently presented by a human figure to imply intellect.   Air signs always oppose Fire signs to match thoughts and ideas to direct and guide our vital energy of creativity into the future.