In ancient Greco-Roman mythology, Medusa was once a priestess serving in the temple of Athena. She was raped by the god Neptune and became pregnant. An alternate understanding is that the encounter with Neptune was consensual but broke her vow of celibacy as a priestess.
Goddess Athena took her vengeance on the mortal, cursing Medusa to become a monstrous Gorgon and to never be able to give birth to her child.
The Gorgons had snakes for hair and their gaze could turn anyone into stone. When Medusa was finally defeated by Perseus and beheaded, Pegasus the winged horse, and Chrysaor the golden giant were born from her decapitated body.
Pegasus features in other Greek myths including the rescue of Andromeda, the defeat of the Chimera, and the creation of the spring Hippocrene. [source]
Pegasus is something pure, it represents the internal essence. Born of a god but petrified in matter. Eternal and ready to be liberated at the right moment. The strength, innocence, and beauty of the horse with the wings of the spirit.