When Perseus was grown up Polydectes sent him to attempt the conquest of Medusa, a terrible monster who had laid waste the country. She was once a beautiful maiden whose hair was her chief glory [long hair is a symbol of chastity: sexual purity; see also Samson] but as she dared to vie in beauty with Minerva [Athena, whose chief attendant is a serpent], the goddess deprived her of her charms [her virtue was lost due to her pride] and changed her beautiful ringlets into hissing serpents [the inverted serpent that opposes Athena; see Judaism: The Two Serpents].
She became a cruel monster of so frightful an aspect that no living thing could behold her without being turned into stone. All around the cavern where she dwelt might be seen the stony figures of men and animals which had chanced to catch a glimpse of her and had been petrified with the sight [upon seeing her tenebrous beauty, they become identified with desire, which gives birth to the ego, a heavy and rigid mental formation that traps the consciousness inside. This is the Brute Stone].
Perseus, favoured by Minerva [his Divine Mother Kundalini, the upright serpent] and Mercury [Hermes, the sexual energy], the former of whom lent him her shield [meditation] and the latter his winged shoes [Sexual Alchemy; the shoes we need to walk the path], approached Medusa while she slept [taking advantage of her mechanical nature] and taking care not to look directly at her [with the risk of becoming identified with desire], but guided by her image reflected in the bright shield [of the stabilized and clarified consciousness through profound stillness of the mind] which he bore [due to many patient years of practice], he cut off her head [the ego, the "I"] and gave it to Minerva [Athena].
Quoted from Bullfinch's Mythology