The cave on Lesbos containing the head of Orpheus functioned for many years as an oracle until one day the head ceased to speak. Much of what it had said had been recorded, however, and this information formed the basis of a new religion that emerged around 600 BCE. Orphism, as it was known, claimed to have at its core the revelations given by the head of Orpheus after it had been detached from his body. The records—known as the Orphica— contain hymns, poetry, and commentaries.
Orphism developed an elaborate cosmogony (a theory explaining the creation of the universe) that focused on the killing and eating of Dionysus by the Titans and Zeus’s subsequent destruction of the Titans, from whose ashes arose the human race, part Dionysiac (divine and good) and part Titan (earthly and evil). Through initiation into the Orphic mysteries, and by living an ascetic life of abstention from meat, wine, and sexual activity, individuals sought to suppress their earthly nature. Full liberation of the divine soul could be achieved only through a cycle of incarnations. Orphism was never a widespread cult, although its ideas were influential.
Thus, in Greek mythology, Orpheus evolved from a gifted musician into a theologian of unassailable authority. The explanation of this development is to be found in the myth itself. Orpheus had achieved something that few mortals had ever done: he had entered Hades as a living being and reemerged from it unscathed. In essence, he had conquered death and thereby weakened its fearful grip on humankind. In addition, Orpheus’s round-trip to the underworld cast reassuring new light on the mystery of death by opening up the possibility of rebirth. Orphian scholars concluded that their hero had been forbidden to turn around and look at Eurydice while they were emerging from the underworld because by doing so he would have been able to see something the gods did not
Orphic Religion
Central to Orphic religious practices was the belief in the transmigration of souls, which, if properly understood and dealt with, could lead to ultimate bliss on the Isles of the Blessed or in the realm of the starry ether. The goal of every Orphic disciple was to learn how the human soul had become stained with evil and the means by which it could be purified. Orpheus had taught the proper rituals and incantations necessary for purification, and he recommended a lifestyle of asceticism that included vegetarianism, a general respect for the value of all life, expiation of sins, and sanctity of conduct. Orphics dressed in white to indicate their aspirations to purity, and they did everything in their power to avoid any form of impropriety. The strict rules of Orphism, together with the prominence it gave to music, caused the cult to be identified with other mystery religions, such as the Bacchanalia and the Eleusinian Mysteries of Demeter. The revelations witnessed by these cults tended to result in joy and the hope for an afterlife of bliss.
Want him to see; namely, the process of regeneration. Thus the very act that stole Eurydice from Orpheus forever is the same act that revealed to him the secret that all humans would like to share.