Egypt was the gift of the river, the Greeks said, and the Egyptians knew it better than anyone. Their country was a green ribbon strung through one of the driest deserts on earth, a land where rain was a rumour, and everything, every loaf, every ox, every child, depended on the flood. Each summer, when the heat was worst and the fields lay cracked and bare, the river began to rise. For weeks the water climbed, spilling over the banks sheet by sheet, until the valley was a shining lake dotted with villages on their mounds, and when the water sank back it left behind a skin of black silt, soft, wet, and fat with life. The Egyptians called their country Kemet, the Black Land, after that gift of mud, and the deserts on either side Deshret, the Red Land of death. A good flood meant full granaries; a low flood meant hunger; a monstrous one smashed the dykes and drowned the villages. Nobody knew where the water came from, this miracle out of the deep south, and so the Egyptians did what they always did with the things that fed them: they made it a god.

They pictured him as abundance made flesh. Hapi is a man with the heavy breasts and round belly of a nursing mother, his skin painted blue-green like deep water, his loins girt like a fisherman's, his crown the papyrus plant when he is the flood of Lower Egypt, the Delta of the north, and the lotus when he is the flood of Upper Egypt, the long valley of the south. In his arms he carries tables heaped with the river's gifts, fish and fowl, sheaves and lotus blooms, or he pours the flood itself from two tall jars. On the bases of royal thrones he appears doubled, two identical giants of plenty, one northern, one southern, kneeling to bind the plants of the Two Lands around the symbol of the windpipe and lungs, the sign of union, so that the king sat upon a knot of plenty holding the country together. He shares his name with Hapy, the baboon-headed son of the falcon god Horus who guards the lungs of the mummy in the canopic jars, but the two gods are no relation. The Nile's Hapi belongs to no family, has no parents and no children, because he is not a character in a story. He is the story's weather.

His home was at the First Cataract, the churning rapids at Aswan where Egypt began, for the flood came out of the south and the south began there. Beneath the rocks, the Egyptians said, lay the caverns of Qerti, two whirlpools where the god dwelt and from which the inundation poured, and the gatekeeper of the flood was Khnum, the ram-headed potter god of Elephantine, the island at the rapids, who shaped mankind on his wheel. A stela carved in the Greek era, but claiming to record the days of Djoser, the pyramid king of the Third Dynasty, tells of seven years of famine, the river failing and the people in despair, until the king dreamed of Khnum and the ram god promised to open the gates: the Nile would rise, the fields would laugh, and hunger would end. Every year the priests and the people watched the Nilometers, the stone staircases cut into the riverbank, reading the rising water cubit by cubit the way farmers read the sky, and every year the first sign of the god's coming was not water at all but a star: Sirius, the brightest star in the sky, which the Egyptians called Sopdet, rising at dawn just before the flood. The oldest story said the flood began with a tear, for Isis wept for Osiris, her murdered husband, and her teardrop fell into the river and made it rise.

He had no great temples, because his temple was the riverbank, and no priesthood to speak of, because every Egyptian was his worshipper. But he had a hymn, and it is one of the loveliest things left by Egypt. The Hymn to Hapi calls him the father of the gods, the maker of barley and emmer, the lord of fish and fowl, and it rolls like the flood itself: when he rises, the land rejoices, every belly is glad, every jaw is chewing, every tooth is grinding; when he is sluggish, the whole land shrinks, the great go hungry, and children weep. Men threw offerings into the rising water, bread and cakes and flowers, and the festivals of the inundation filled the summer with music. He was, in the end, the most practical god in Egypt, the god you could measure on a staircase, and perhaps for that reason the most beloved. You did not need to believe in Hapi. You only needed to watch the river rise.

The Greeks who came to Egypt looked at the inundation and saw a river god like their own, and they named him Neilos, father of the Nile, and carved him as a reclining giant with a cornucopia, a sphinx at his side, and sixteen little children climbing over him, one for each cubit of the perfect flood. Rome copied the statue and scattered Nile gods across the empire, and the image of the plump bringer of plenty flowed into every fountain and river god of European art. In Egypt the flood kept rising, year after year, century after century, until the 1960s, when the engineers finished the Aswan High Dam and Lake Nasser spread over the cataracts, and for the first time in five thousand years the inundation stopped. The god of the flood outlived his temples by two thousand years and was ended at last not by forgetfulness but by concrete. Yet every green field in the valley still feeds on his old gift, the silt of ten thousand floods, and somewhere beneath the lake the caverns of Qerti lie drowned, waiting for a god who is not coming back.