Think of silvery-white, malleable and fluid, ever-alive quicksilver. Think of the Roman messenger-god Mercury who sent messages from gods to humans, yet was an unpredictable trickster. Such quirks make for a richer, more complex being. In astrology, Mercury is further involved with trade and travel, is associated with youths and relatives, and excels in all kind of communications. Mercury's ruler-ship is shared by air-sign Gemini (May 22-June 21) and earth-sign Virgo (August 24-September 22). Both are highly mental and verbal signs flavored either by the air or earth traits.