The recent possible discovery of the person to whom Shakespeare dedicated his Sonnets - the mysterious "Mr W.

H." - sent me back to my copy, which comes with its own inscription, several years old now but evergreen still. Mr W H, claims American researcher Geoffrey Caveney, was William Holme, a publisher friend of Shakespeare's printer who was involved in the theatre. He died in 1607, two years before publication of The Sonnets, which Caveney suggests might explain the way the dedication is written, as if for a funerary memorial. Given the portentousness of many of the sonnets, and their preoccupation with the effects of time on beauty and love, this makes it an even more appropriate dedicatee than those previously suggested, including Henry Wriothesley, Earl of Southampton, and William Herbert, Earl of Pembroke. It also makes it much less likely that Holme was the "fair youth" to whom many of the sonnets were written, whose identity continues to titillate scholars.

As sombre as they are heartfelt, the Sonnets are not everybody's idea of what love poems should be. Many of them remind us of the approach of death, something that preoccupied - and perhaps sharpened - Shakespeare's mind. "When I behold the violet past prime,/ And sable curls all silvered o'er with white," he writes in Sonnet 12. "Since brass, nor stone, nor earth, nor boundless sea,/ But sad mortality o'ersways their power..." he continues in Sonnet 65. In Sonnet 77: "The glass will show thee how thy beauties wear,/ Thy dial how thy precious minutes waste".

I would rather turn to the Sonnets for a taste of love, bittersweet though much of it is, than to the saccharine sentiments of verses written with Valentine's Day in mind. Yet a love poem is not easy to compose, as any will know who have tried to express their feelings in print and, on rereading them, discovered not another Byron or Heaney, but a talent better suited to Hallmark cards.

Why is love so difficult to capture in a poem? Without doubt it is harder today than in previous generations, in part because we are so knowing, cynical, and self-conscious. Shelley and Keats and DH Lawrence could write without hearing a snigger at the back of the room. Whereas now, even fine poets can be crippled by fear of embarrassment. Someone like James Fenton, however, manages to acknowledge this modern malaise, and make something of it in the wry but feeling 'In Paris with You': "Don't talk to me of love. I've had an earful..."

In 'Valentine', Carol Ann Duffy takes this awareness further. "Not a red rose or a satin heart./ I give you an onion..." Explaining her seemingly perverse choice, the poem is tender and wary, hinting at the potential for savage hurt that all passion holds.

Hers is the last in a new collection gathered by the late Dannie Abse in Favourite Love Poems (Batsford, £14.99). Running through the centuries, from the Latin poets to the present, it is a reminder that the love poem could be seen as the apprentice piece of every poet who would be good, or better than good. If they can master this, you might say, then they have the measure of their art.

Personal taste, of course, dictates the poems one prefers. One woman's Duffy is another's Elizabeth Barrett Browning. The level of emotion or explicitness or lyricism one enjoys is deeply personal and alters, year to year, as life deepens or corrodes one's understanding of love, and the ways it can be evoked.

Yet while I have favourites - Thomas Hardy high among them - it is the Sonnets I return to most often. There's little room in these lines for comfort, and even less for complacency. And yet they are imbued with the hope that love - and poems of love - will triumph over all. The bard believed only one thing might possibly defy time and outlast us: "unless this miracle have might/That in black ink my love may still shine bright."