Thus Dionysus presents himself to us in two forms: as the god who vanishes and reappears, and as the god who dies and is born again. The second conception has evolved into the well-known doctrine of the numerous rebirths of the god. Basically, however, both conceptions (his vanishing, which is paired with his reappearance, and his death, which is followed by his rebirth) are rooted in the same idea. Both tell of the god with two faces, the spirit of presence and absence of the Now and the Then, who is most grippingly symbolized in the mask. With him appears the unfathomable mystery of life and death cemented together into a single entity, and the mystery of the act of creation affected with madness and overshadowed by death. This is why he bears with him not only all of the energy and exuberant joy of a life which is at the height of its activity but also his entire destiny.
Dionysus: Myth and Cult, by Walter F. Otto (via dionysian-light)