The planet shares the Ancient Mariner’s predicament. There is water, water everywhere. It is the commonest ingredient of the biosphere. Almost everything that is not water contains it. Yet water is so erratic, so unevenly distributed and so vulnerable to pollution, war and technical failures that both its presence and its absence can kill you. In rhetoric, at least, water has become a cause of wars. In reality, it has been, as coiners of neologisms like to say, ‘weaponised’ – in the Holy Land, for instance, the Horn of Africa and Ukraine. Prophets of global water shortage are in, near or beyond despair. But are they right? Are water wars ineluctably part of the future and thirst an inevitably aggravating affliction for much or most of the world? If so, why?

James Fergusson focuses vividly on what by planetary standards may seem a little local difficulty, but he presents it plausibly as a parable for the world. His title, In Search of the River Jordan, evokes the lyrics of spirituals, in which the Jordan is a symbolic river – ‘de ol’ stream dat I long to cross’ in Oscar Hammerstein’s version of an overworked black’s death wish. The Jordan of enslaved imaginations was a ‘deep river’. In reality, it was once wide and rapid. Not so now after over-exploitation, except where engineering has sped up what otherwise varies between a sluggish, muddy slither and a trickle – the ‘dirty brown ditch’ that shocked Fergusson when he began work. In some ways, his book belongs to a familiar genre: the author’s pilgrimage into his own past or roots. Arthur Balfour, his great-great-great-uncle, makes occasional appearances in a minatory or elegiac role. David Ben-Gurion called Fergusson’s great-grandmother Blanche Dugdale the ‘New Deborah’ because of her championship of the state of Israel.

Despite his Zionist ancestry, Fergusson can see, as he puts it, from ‘both ends of the telescope’. He is fair and compassionate in scrutinising the insecurities and struggles that make for misery among groups that trade blood for soil in the Holy Land. He has a fine eye for