'Speak, that I may see thee,' Ben Jonson said. 'Language most shows a man.' A playwright used to casting, he is also the crispest and one of the most considerable poets of his age. In a person's manner of speech, whether in verse or in dialogue, he might detect much: the accents and dialect gradations of geography, for one thing; sometimes class; sometimes those little eccentricities - not impediments, exactly - that make a voice unique; sometimes a quaintness of usage which denotes age or affectation. He inferred what was unique, but more, in voice he detected the larger expressiveness of which a person is capable: not what makes for difference but what makes for commonality, for communication.

There is a seeming cheat involved when you have the advantage of the poet's voice. The poem comes off the page. You hear, as well as the things Jonson listened for, the prosodies as the poet intended them, often quite different from those that affect the pensive readerly tympanum. At a time when English, like late Latin, is diversifying into dialects that will themselves become languages, the seeming cheat becomes almost a necessity.

It is hard for a specifically English ear not to mishear, for example, the prosody of Wallace Stevens. We tend to find in him a relatively regular iambulator. But his own recorded readings transform an English reader's sense (whatever that English reader's accent might be) of the prosody. The prosody Stevens's voice reveals can be distinctive, and hearing it changes the charm of his verse. The metrical poison so many poets imbibe with their Stevens is not his poison, but one drawn out of their own dialect, or their own conditioned expectation, due to the deceptively familiar surface of his poems.

The first time I listened to Stevens's 1954 recording of 'The Idea of Order at Key West' the scales fell from my ears. Each line is endowed (in a quite un-mechanical way) not with one but with two caesuras. This breaks the apparent tyranny of the iamb, creating a suspension or a stillness, changing the emphasis and climax of the line. A driving iamb can be imposed upon the verse, but it is not inherent. What is inherent is something tentative in the emphases it gives. Had Stevens been a calculating modernist he might have laid out his lines in the indenting triplets favoured by Williams. He was not interested in such effects.

These reflections on what hearing a poet read can sometimes add to a poem are prompted by the launch in London and into cyberspace of a fabulous new resource which will develop and which, without vulgarity, dumbing down or compromise, will bring poetry close to anyone, from the aficionado and specialist to the vaguely curious.

Ever since Andrew Motion became Poet Laureate he has been labouring, with Richard Carrington and others, to create the Poetry Archive (www.poetryarchive.org). They raised considerable financial support, travelled the world gathering voices, passed through the eye of the Copyright Law needle. Some poets they reached 'just in time', beating the reaper by a hair, and for a time their approach was greeted with a shiver of fear by older writers.

On 30 November we all became their beneficiaries. At the British Library the Archive was formally launched. Its aims, in Andrew Motion's words, are 'to conserve voices that might otherwise be lost... to demonstrate that the sound of a poem is as important to its existence as whatever the words might mean when we read them on the page...and to provide entertaining advice to teachers and students about the meaning and pleasure of poetry'. This is not a narrowly British enterprise: it includes Anglophone poetry from around the world and may one day come to include poetry in other languages as well. Here, free of charge, anyone with access to a computer with speakers can hear the voices of major poets, past and present, and access text and information of many kinds.

The pietas represented by this magnificent effort, pursued against so many odds by the Laureate and his team, broadens spectacularly the access people have to the poetry of the last hundred years and could change the ways in which it is taught, learned and loved. This Laureate and his colleagues are not mere cheerleaders for poetry, its marketing agents; they have made a real and durable difference to the art by creating a lasting, irreversible point of access to that art. Exegit monumentum aere perennius may be a just epitaph for Andrew Motion, this being (along with his own poetry) the monument. He had a vision and had the gumption to use the Laureateship to make it real: a wonderful and durable gift for us all at this season.