Salt Water is his most intense exploration yet of this metaphor and of the element that both sustains and threatens life as in

Salt Water is his most intense exploration yet of this metaphor and of the element that both sustains and threatens life (as in Heaney's Seeing Things). There are three major items here, each of which would have provided a powerful thematic centre on its own: the long opening poem, "Fresh Water", follows the Thames from its source to London, and then back again in an imaginative narrative about Ruth Haddon, the writer's friend, drowned on the Marchioness. The second major piece is the title-poem, which tells in interspersed quatrains the terrible 12th-century legend of the Orford merman who failed to speak even under torture and was "slid tail-first" back into the sea. And the third is the book's "Part Two", a prose account of Motion's journey by sailing-ship from Tower Bridge to Naples, retracing Keats's voyage to his death in 1820, undertaken as research for Motion's biography of Keats (memorably filmed in 1996 by the BBC).

For a number of reasons, Motion's prose memoir far transcends the television version, compelling as that was. As poet-novelist, Motion is primarily a writer, and a highly self-examining one. Indeed one of his most affecting works was the prose memoir of his mother's death in Poetry Review (there are strikingly parallel synergic family memoirs by Michael Longley and Craig Raine). In Motion's Keats voyage we become progressively more distanced from the dying Keats, at least in any way we might have anticipated finding him.

Certainly some of the Keats quotations express the book's centre: "Is there another life? Shall I awake and find all this a dream? There must be - we cannot be created for this sort of suffering." And at the end: "O what an account I could give you of the Bay of Naples if I could once more feel myself a Citizen of this world." But Motion can make a Dantesque return to this world, denied to Keats: a distinction of absolute importance. An early poem of Motion's begins "It was straight out of Conrad but true." The strange strength of this magnificent brief memoir - it takes 54 pages - is that a journey which is described with such unportentous graphicness can also be a progress in imaginative self-abnegation. Art concealing art indeed! For an example of the unportentous, Motion in a fit of deep gloom (characteristically described with neither self-pity nor self-accusation) is greeted by one of the crew who "belches vilely" and cheerfully remarks "Wind!"; the author comments laconically, "I want to stick a marlin spike up his arse and throw him to the shark which has just idled past, its fin slick and alert." Hardly a mystical reflection; yet the Conradian theme traces the highly interior progress of the mystic's visionary boredom. "At some stages it occurs to me that I've never been so bored in my life But I don't want to be anywhere else, doing anything else. My boredom isn't painful - it's like a trance, a rapture."This is not the book's conclusion. The dying Keats, alas, was not able to become again a Citizen of the World.