Gemini is the sign located between Taurus and Cancer, showing a picture of two figures seated side by side, and almost all cultures saw this constellation as a unity of two. The old Egyptians called the sign the 'Two Stars' or 'Pimahi' which means 'The United'. The Hebrew called the constellation Thaumin, which also translates as The United. The glyph shows two wands bound together as a symbol for conflicting contradictions in compromise, and it also reminds of an ancient script scroll, mediating duality mediated through intellect.

The glyph also reminds strongly of the glyph for Ka, the Egyptian principle of duality which represents the spiritual double in a human, the combination of soul and matter. The Egyptian zodiac image shows the Gemini as a man and a woman, male and female, another way to symbolize duality.

In Greek mythology, Castor and Pollux (Polydeuces or Dioscuri) were the sons of Zeus who seduced their mother Leda in form od a swan. The brothers gained fame in Sparta, Castor as a horsetamer and Pollux as a boxer. They sailed with the Argonauts, participated in the Calydonian boar hunt, and later helped to save their sister Helena, who had been kidnapped by Theseus. When Castor was killed, Pollux was devastated and didn't want to live without his brother, asking Zeus to help him to be with his brother forever. Zeuse placed them both in the sky, Pollux as the Morning Star and Castor as the Evening Star. The twins were highly esteemed by the Romans.