The sign of the twins is an air sign and ruled by quick-witted Mercury, the God of communication, trade and trickery. Mercury always follows his curiosity and never sits still.
The twins are a ‘dual sign’, which implies that there are two sides to their character. In Greek mythology, the most famous twins were Castor and Pollux, sons of Zeus by the Spartan Princess Leda.
Zeus had disguised himself as a swan before he ravished her. Since Leda was a mortal, Castor and Pollux were born (hatched, actually) as half-gods, Castor a mortal, while Pollux was immortal. The twins were inseparable, but on one of their adventures, Castor died. This was unbearable for Pollux and so they pleaded with Zeus to let them both die. However, since it is impossible for an immortal to die, this was no solution. Instead, touched by their devotion to each other, Zeus offered them a different deal. They could share Pollux’s immortality. They were to spend alternate days as immortals among the Olympians and in Hades among the mortal souls. Every time they switched places they could spend a little time together.
Zeus eventually granted them a place among the stars and made them both immortal as the constellation of the twins.
This dual nature – being both mortal and immortal, says a lot about Gemini’s ambivalent sense of self. Half the time he is flying high and fancy-free in a divinely inspired ecstasy in the world of ideas, unsullied by actual flesh and blood reality. But the other half of the time he recognizes the limitations of his mortal existence, and it is crushing. The butterfly feels weighed down by earthly existence with all its tedium. And thus, Gemini vacillates between these two states of mind but is rarely aware of both at the same time. Luckily, his emotional states change quickly and he does not brood or wallows for long. As soon as something new and exciting comes along anything that might have cast a cloud on his blue skies, is soon forgotten.