Main principle: to split and quicken (quicksilver), duality, logos. Mercurys main purpose is to act as the go between for all dualities and all types of opposites, such as hot and cold, wet and dry, light and dark, hard and soft. For this reason it is none of these principles in itself (though it tends slightly toward dryness), but rather mimicks whatever principles happen to be most prevalent. It signifys transit, communication, language, and mental capacity. It is neuter as to sex.