Some years ago, I re-read, in rapid succession, Paul Muldoon’s first eight collections, up to and including Hay (1998).

What emerged, more clearly than previously, was the considerable strangeness of his genius and (since something of the temperament must always be in work that succeeds) his person. Across the oeuvre, I began to discern a number of distinct strands of imaginative temper, feeding off and into each other: the straight Muldoon; Muldoon the post-modern seanchaí; Muldoon the magus of textdom, of pure writerliness and linguistic probes; Muldoon the umbilicus to childhood imagination, or the chameleon of influences and assumed voices; Muldoon the quotidian chronicler; Muldoon of the sexual braggadocio ... and so forth.

I took this demonstrative multiplicity, ironically, as a sign of fundamental imaginative self-honesty - for, despite all the arabesques of technique and ludic high-jinks, and much more than many apparently confessional poets (who very often work to PC notions of poesy and propriety), with Muldoon you really do get an authentic insight into the deeper psycho-dynamics of the underlying personality, some of whose dimensions can be more than a little unsettling, especially in matters of sexual relations.

From his debut in the aptly-named New Weather (1973), a unique combination of two salient brilliancies - a given and a gift - has characterised Muldoon’s work. Not a limiting “correspondence course” between poetry and actuality, but the precise weather of the self, an inward cartography, the sensation of things as they are actually perceived or imagined - the poem’s ludic, and lucid, interchange of language and reality - has been the fundamental temperamental given. Inseparable from this second nature is the Muldoonish gift: the dazzling ingenuity and self-reflexivity of his formal virtuosity; the relentless pursuit of new musicalities of tone and form and metaphorical intelligence; the love of Joycean wordplay, serendipity, obliquity and recondite vocabulary; the unimpeachable slide and drive of his image-sound momentum.

Part of the pleasure in the later collections, therefore, is seeing which of these recombinant Muldoons come to the fore within whatever new démarche of making strange and making well he has embarked upon. Here, in Horse Latitudes, his 10th collection, even more concertedly than in his previous, Moy Sand and Gravel (2003), Muldoon the formal maestro, flexing his extraordinary versatility, is the clear titular presence - though shot through too, basso continuo, with fleeting riffs of great emotional charge, as in the straight Muldoon of such earlier masterpieces as “Incantata” and “Third Epistle to Timothy”.

The title sequence, a fifth of the collection, consists of 19 sonnets revamping that form, each titled with a historical battle beginning with B, the whole launching the thematic navigations of the book. The Horse Latitudes are the equatorial doldrums, a zone of betwixt-and-between, mid-Atlantic or mid-Pacific, where shipping and whalers were traditionally becalmed, and sailors threw horses overboard to conserve on water and provisions.

The servant horse or mule, a submerged Pegasus image, is long-standing in Muldoon; and here the equine geographics serves an understanding of the imagination and indeed life itself as belonging, mulishly, to the double light of language and reality - two places at once, or one place twice - whilst intimating a personal midpoint becalmed, after youth’s leviathan movements, in the older doldrums of American suburbia and its imperial entanglements. A second sequence set in still-colonial Bermuda, “90 Instant Messages to Tom Moore”, using the rhymed haiku as bijou text message in a dialogue with the classic nationalist poet and song-maker, further anchors the mid-Atlantic, post-nationalist, bifocal buoyancy of the whole rigging.

Along with a trademark concluding long-poem, “Sillyhow Stride”, the two sequences advert to what is perhaps the essential flavour of the later Muldoon: that double-light, that Janus-head, that tug-of-war between the “two places”. Hence these latest annals of the imagination abound in lashed juxtapositions: the Old World and the New; the Pygmalion of the past made present; ancestry and its traductions; public fields of battle, private fields of grief; horse-slaughter and our own loss of breath; the interplay of art with the caul of death that dogs its every stride.

Each of the other 27 poems also embodies, without exception (though with an occasional dip), either an entirely new or half-novel form involving rhyme-scheme, lineation, repetition, refrain, phrasing, riddling, and/or some more abstract syntactical structure. In several, Muldoon explores the Dylanesque limits of poetry’s kinship with song; in another, he uses a long concatenation of cliches for a brilliant codology of Old World essentialism. In the boxing-clever of such formal nimbleness, he effectively legitimates the poetic potential of any linguistic register found within his own high lucid-ludic persona - an exceptional achievement, but also deeply fertile for peers and successors.

In the long history of prosodic innovations in English, from Chaucer to Watt to Charles Wright, genuinely new poetic forms are exceedingly rare. Great poetry has depended not so much on invention of the new as reinvigoration of the old; to do both, then, belongs to the rarest of talents. In proffering a primer for new poetic directions, Horse Latitudes, like its two predecessors, actually dissolves the position-taking of “formalist” and “free”, since its author demonstrates just how individually protean form can be for a true master. It slowly dawns that Muldoon’s formal project is now nothing less than extending the entire rubric of the poem in a way comparable (strange to say) to the prosodic revolution once wrought by the sprung rhythms of Gerard Manley Hopkins.