Rapture, By Carol Ann Duffy

That's the wise thrush: he sings each song twice over,
Lest you should think he never could recapture
The first fine careless rapture!

The quote says it all. This book of wonderful love poems is also a love poem to poetry itself; to writing love, as well as making it. The best love poetry always seems direct and fresh but underneath is sophisticatedly literary. Duffy's double entendre reminds us how poems overlay or writes "over" experience. The affair may be "over"; the song will be sung over in another sense. Experience matters: it comes first, Duffy's poems always seem to say.

Experience, the world, feeling thrusts its way ruthlessly to the light like pioneer scrub. But to the artist, at least, "art" - that secondary thing, the apparent after-comer - matters as much. "Only art now" begins the third-last poem, "Art":

our bodies, brushstroke, pigment, motif;
our story, figment, suspension of disbelief;
the thrum of our blood, percussion;
chords, minor, for the music of our grief.

This whole book, whose see-saw internal balances and rhymes you see working in that quatrain, is a superb demonstration of such "only art": Duffy's formidably inventive artistry, her dedication to the craft and tradition of poetry, and above all the love poem.

The three strong books that made her name in the Nineties blazed with voicings; with dramatic characters, a bomber, a psychopath, an American buying Manhattan. This voicing power emerged again in The World's Wife, along with the same sharp humour, social criticism and satire. But those collections ended in love poems and you felt that this, in the end, was what really drove Duffy's work. In Rapture, it comes to its full flowering: ruthless, sensuous, tender; utterly modern, utterly classical.

One of the originalities of Rapture is a spotlight on everything rhyme stands for, both in life and in art. "I hear your name/ rhyming, rhyming,/ rhyming with everything." Rhyme, in our supremely mongrel uninflected language, which draws its vowel sounds from so many different sources, is one of the most significant ways in which words as well as people partner each other to create relationships that are more than the sum of their parts.

Inevitably, then, the form that dominates Rapture is the sonnet, that magical shape so suited to reflections on love, which established its classical rhyming patterns and their hold on love poetry in the Renaissance, Italian and English. It was revivified (especially by Meredith) in extended sonnets of 16 lines, then truncated, broken, and made to sing new tunes in the 20th century, especially in America, and is still vigorous today. Out of 52 poems here, 18 are classical 14-liners, many more are extended or shrunken sonnets.

Even the 14-liners are inventively varied. Often Duffy breaks a central line, so it looks as if we are casually beginning a new stanza when in fact we are not - just as in the ambiguous stages of a love affair. Duffy is supremely sophisticated in making sound and form match sense and context. Talk of "Fifty ways to leave your lover": here are 50 ways to break, disguise and celebrate your sonnet. And through the sonnet, your love.

Fantastic, to see one of our best and most popular poets going from strength to strength in subtle literary originality, echoing traditional craft from Shakespeare to MacNeice, while making poems that will sound sweetly to all: "their silhouettes/ simple as faith".

Ruth Padel's 'Tigers in Red Weather' is published by Little, Brown