(_b_) To dissociate a ghost from mankind is especially easy if his tomb has been forgotten, or if he has no tomb. As the drowned have no tombs, they easily become water-demons. Tombs must often be forgotten in consequence of migrations. In Central Melanesia both ghosts and spirits are recognised; but in the west worship is directed chiefly to ghosts, in the east chiefly to spirits. As migration has been from west to east, the tombs of ancestors can no longer be pointed out by the eastern islanders, and so their ghosts may have become spirits. In Tumloo (northern New Guinea) there are temples of spirits (all female) distinct from ancestral ghosts, and on the banisters of ladders leading up to these temples there are ornamental figures of ape-like animals; the architecture of the temples points to a former superior culture.[200] As there are no apes in New Guinea, these figures and temples may indicate a former residence under better conditions in Java or Borneo; and the spirits with which they are associated may be ancestral ghosts whose tombs and other earthly vestiges have been forgotten in the migration. (_c_) We may see another way in which a ghost may become a pure spirit, if we suppose that as a ghost he had attained to some measure of worship, but that with the rise of new gods (by conquest, or by the reputation of being more helpful), or by his being himself too good to be worth worshipping, his rites have been neglected and his legend forgotten. Then he is no longer remembered as a ghost, or ancestor. (_d_) It may be thought honourable to a god to deny that he was ever a man. (_e_) The construction of a world-myth makes it necessary to begin somewhere with some one; and whoever becomes the first being, it is necessary to deny that he was ever begotten. But there may be inconsistent stories: the supreme being of the central Esquimo is a woman, Sedna, who created all things that have life; but other traditions give her a human origin.[201] Similarly, in drawing up the genealogy of ancestral gods, we come at last to one who was never begotten. Such is Unkulunkulu of the Zulus, generally said to have sprung from a bed of reeds.[202] _B._ Spirits that were never incarnate, but have been imagined by analogy with ghosts already propitiated: