the mystes, departing from the sanctuary of his experience of androgyny (beyond the opposites not only of femininity and masculinity but also of life and death, time and eternity), must resume his place in the light world without forfeiting the wisdom gained; and exactly proper to the sense of such a passage is the dual symbol of the twins, immortal and mortal, respectively, Pollux and Castor.
Campbell argues that the Castor-Pollux dyad at the culmination of the mystery initiation symbolizes the mystes’ necessary re-entry into mortal existence while retaining the transcendent wisdom of androgynous experience.
, Creative Mythology: The Masks of God, Volume IV, 1968thesis