Nile River

Every summer, before the dams, the river rose, spread across the valley floor and fell again, leaving a layer of silt that made the narrow strip beside it one of the most productive places on earth. Egyptian religion organised itself around that event. The civil year was divided into three seasons named for it, akhet the inundation, peret the emergence of the land, shemu the harvest, and the new year was tied to the reappearance of the star Sothis at dawn, which coincided with the flood's beginning.

The flood was not itself a god so much as a divine act. Hapi, shown as a heavy figure with pendulous breasts and a belt, personified the inundation and was thanked in hymns for filling the granaries; the water was also spoken of as the effusion of Osiris, whose death and return the annual cycle repeated, and as the tears of Isis mourning him. Richard Wilkinson's survey of the Egyptian pantheon notes how many gods carry some responsibility for the river without any one owning it.

Its measurement was a religious as much as an administrative act. Nilometers, stepped shafts cut at temple sites from Elephantine to the delta, recorded each year's height, and the tax assessment followed from it. A low flood meant famine and, in the royal ideology, a failure of the order the king was supposed to maintain, which is why the seven lean years of the Egyptian tradition preserved on the Famine Stela are told as a religious crisis rather than a meteorological one.

Christian Egypt kept the river's rhythm and changed its meaning. The deserts on either side of the valley became the birthplace of monasticism: Antony withdrew into the eastern desert in the late third century, Pachomius organised the first communities in the Thebaid, and the monasteries of Scetis in Wadi Natrun, west of the delta, have been inhabited continuously for some sixteen centuries. The Coptic Orthodox Church still uses a calendar whose year begins in September with the flood season and still prays, in a set petition, for the waters of the river to rise to their proper measure.

Under Islam the river remained the country's central fact and its ceremonial one. The cutting of the dam at the Khalij canal in Cairo, when the Nilometer on Rhoda Island registered a sufficient flood, was the great annual festival of medieval Cairo, and the custom persisted in altered form into the modern period. Upstream, the Blue Nile rises at Lake Tana in the Ethiopian highlands, whose island monasteries hold some of the oldest manuscripts of the Ethiopian church, so that the river links two of the oldest Christian traditions along its own length.

The Aswan High Dam, completed in 1970, ended the inundation. Lake Nasser drowned Lower Nubia, its people were resettled, and the temples of Abu Simbel and the island of Philae were cut apart and rebuilt on higher ground in an international salvage campaign.