The story of Virgo:

One of the few signs not represented by an animal, Virgo's origin stems from the Tale of Pandora. Virgo is the representation of the goddess of purity and innocence, Astraea. After Pandora opened the jar and let loose all the evil's unto the world, the gods who lived on the earth fled back to the heavens and away from the evil's of the earth. Astraea was the last to return to the heavens and as a rememberance of innocence lost, Astraea was placed amongst the stars in the form of Virgo.