In Horse Latitudes we enter bleak Ancient Mariner territory, the ship becalmed in the zone in which, legend has it, after windless weeks sailors throw horses overboard 'to conserve food and water' (though why they do not eat them puzzles me). In such doldrums the poet, now in his mid-fifties, shares the standstill with anxiety (public and private), fear, anticipation, memory. He temporises, he fritters away the time, he grieves but keeps the tears inside his eyes, he whittles bits of wood and ivory. All this he does in a language full of debts and borrowings, of laughter and invention. The past bubbles up like milk overflowing on the stove, or dark water gurgling back out of a drain. What is serious is the situation, and what it discloses about the 'now' we share.

The poems do not surrender us to gloom. Muldoon is a grey ing Harlequin. Friends have given him scraps and offcuts from their wardrobes. He patches together something that covers his nakedness. He has made his motley elegant; indeed he has devised several costumes. He recalls his Columbine, or here, Carlotta, a beloved who died of a wasting illness. She persists, woven into memory and dream, part of his conscience.

If Muldoon is Harlequin, old Pantaloon's servant, then Pant alone may be Seamus Heaney. There are certain tones and strategies that, for Muldoon, are out of bounds. They belong particularly to Heaney, to Michael Longley or to Derek Mahon. Muldoon won't play their tricks, though he could if he wished. He has his own tricks, wholly and inimitably his, which is why he has so many imitators. We might confuse lines of Heaney with those of Longley or Mahon. But Muldoon is wholly his own man, a jester in the earnest world of his elders, making sense in quite a different way from theirs.

His poems do not avoid the public sphere. The legacy of the troubles he lived through in his youth in Northern Ireland is not a focus on Irish themes and symbolic landscapes, but a vulner - able openness to a wide world. Ulster was an apprenticeship: sensibility and conscience came of age there. Now he lives in Dubya's United States. In the tense, misshapen sonnet 'Hedge - School', with its title debt to Heaney and its allusion to Ireland, he evokes in caricature the traditional hedge schools, then wonders if his daughter in her 'all-American Latin class' will have to learn to conjugate Guantanamo, amas, amat. He fleetingly evokes The Comedy of Errors, which she will encounter in class: Luciana's line, 'headstrong liberty is lash'd/with woe'. The poem, 'set' in St Andrews, addresses his beloved sister, suffering from terminal cancer. He tells her of the seventh-century bishop buried there who shares their surname. He wishes he had opened the OED he saw in the bookshop and looked up the root of the word metastasis. The lines of Luciana that he does not quote hover over the poem: 'There's nothing situate under heaven's eye/But hath his bound, in earth, in sea, in sky.'

Such poems don't just say things. We read them for what they do with and to language, how they engage and transform clichés, how they subvert genres not in a mere spirit of play, but to make them serviceable in new ways. Thus 'The Mountain is Holding Out' gradually fills a whole landscape with petulant personifica - tion ('The plain won't level with me'). The images are invested with sinister agency - the lake, the river - and as in so many of Muldoon's poems, the end is the beginning. 'The Old Country' is an extended sonnet sequence liberating clichés, their music and their impacted meanings.

Popular culture in the old sense - riddles, songs, nursery rhymes, jingles - is part of a prosody time after time predicated upon the sonnet form. Just as he wrings sense out of tired phrases, so he finds in the sonnet new ways of making connection. He does the same with the quatrain, the couplet and the rhymed haiku which he has made distinctively his own. '90 Instant Messages to Tom Moore' are haiku of the sort an orien - tal John Donne might have composed, seasonal and metaphysi - cal, imagistic and carnal. The poems point not only to the world out there but also to the world of words themselves:

The sput-sputter-sput
where the idling fish torcher
lights on halibut.

This sentence, without a main verb, tells us about the haiku form and the language it comes from. The engine idles (in sound and sense) as the fish torcher does, his torch a light and flame, the illumination reflexive, on language itself, with that curious rhyme. These haiku are at sea, with barracuda and other monsters of the deep, with crabs (of both sorts) and eels. Taken together, they seem to plot (with no specific, over-arching plot) the coming apart of an intimacy. The sequence ends morosely, but the tone is one of accessible sadness. There is space for the reader in this reiterative template:

Completely at odds.
We're now completely at odds.
Completely at odds.

Muldoon's formal play produces the form of 'Perdu', one of the most amusing and moving poems in the book, pressing on from couplet to couplet by repetition. The fourth grows out of the third. It reads: 'My five-year-old had eyed me through and through:/"Tell the buriers to bury me with you."' Each stanza has its own narrative. They add up, though it would be foolish to try to summarise what they add up to. Just as, in a short review, it would be foolish to engage with the longer sequences, in particular the baffling, beautiful 'Horse Latitudes' itself. Suffice it to say there are horses and horses. And horses. There are battles, and Carlotta, and falcons, falchioneers, fanfarons, chain-mail, wet-suits, and a quite remarkable rhyme scheme with couplets like waistcoat buttons fixing the central lines, but loose at top and bottom, thus: abcddcbeeffabc.

For all his invention and evasive wit, Muldoon is never less than hospitable. His poem 'Riddle' is a riddle, but an easy one, which lures us along and discloses how his art works, by hint and by grace, repetition and inclusion. The essays are similarly turned towards us. At one level, they are about how he reads, and we can infer how he writes, the kinds of common knowledge and privileged knowledge that are sealed into poems. The essays focus on poems and, quite unabashedly, read them. What makes the approach compelling is the weave of narratives: the story of the poem, of the poet, of the poem's world and the poet's world - intentions, influences, the process of inference and response. 'What is the good of criticism?' asked Baudelaire: to 'transform my pleasure into knowledge'. Usually the pleasure is in the poem, sometimes in a puzzle. Muldoon's essay on Ted Hughes's 'The Literary Life', a revenge on Marianne Moore for her refusal to engage with the poems of Sylvia Plath, probes literary history and a complex, triangulated psychology. It is exemplary writing, illuminating in all directions. His account of Robert Lowell's 'imitation' of Montale's 'eels' makes Muldoon's own eels shimmer and writhe with more than literal luminescence.

MICHAEL SCHMIDT