It was believed to be essential that human beings should share the universal sorrow caused by the death of a god. If they remained unsympathetic, the deities would punish them as enemies. Worshippers of nature gods, therefore, based their ceremonial practices on natural phenomena. "The dread of the worshippers that the neglect of the usual ritual would be followed by disaster, is particularly intelligible", writes Professor Robertson Smith, "if they regarded the necessary operations of agriculture as involving the violent extinction of a particle of divine life."[108] By observing their ritual, the worshippers won the sympathy and co-operation of deities, or exercised a magical control over nature. The Babylonian myth of Tammuz, the dying god, bears a close resemblance to the Greek myth of Adonis. It also links with the myth of Osiris. According to Professor Sayce, Tammuz is identical with "Daonus or Daos, the shepherd of Pantibibla", referred to by Berosus as the ruler of one of the mythical ages of Babylonia. We have therefore to deal with Tammuz in his twofold character as a patriarch and a god of fertility. The Adonis version of the myth may be summarized briefly. Ere the god was born, his mother, who was pursued by her angry sire, as the river goddesses of the folk tales are pursued by the well demons, transformed herself into a tree. Adonis sprang from the trunk of this tree, and Aphrodite, having placed the child in a chest, committed him to the care of Persephone, queen of Hades, who resembles the Babylonian Eresh-ki-gal. Persephone desired to retain the young god, and Aphrodite (Ishtar) appealed to Zeus (Anu), who decreed that Adonis should spend part of the year with one goddess and part of the year with the other.