Wordsworth championed `powerful feelings'; so did Diana. Jonathan Bate asks if New Britain has gone New Romantic
Wilde has been sluggish at the box-office. There is no place for the Marquis of Queensberry in Tony Blair's Britain. Even Oscar's slick epigrams seem out of kilter with the time. "The first duty in life is to be as artificial as possible," said the man who epitomised the 1890s - "what the second duty is no one has yet discovered."

The lesson of the first week of September 1997 was the exact contrary: the first duty in the face of death is to be as sincere as possible. And the lesson of the first of May? Perhaps: the first duty in politics is to be as sincere as possible and the second is to sound sincere even when you are not.

Another sage of the 1890s, Sigmund Freud, remarked that however tempestuous our relationship with our parents may be, we always love our grandparents. Perhaps a similar pattern asserts itself when we come up against the fin de siecle: the 1990s are looking less and less like the 1890s, more and more like the 1790s.

As in 1789, so in 1989: revolutions across Europe. As in the 1790s, so in the 1990s: uncertainty and navel-gazing with regard to Britain's place in a rapidly changing world. The Scots finding a voice: Robert Burns then, the referendum now. Stirrings of a united Ireland: from Wolfe Tone to Gerry Adams. And the English? For them, something quieter: a revolution less of politics than of spirit.

Jean-Jacques Rousseau laid the intellectual foundations for the French Revolution, but an even profounder legacy was his influence on the cult of sensibility and the great shift in cultural mood which we call Romanticism. After Rousseau, it became acceptable for grown men to cry. Suddenly it was hip to unbutton your frock-coat and throw away your powdered wig. Touchy-feely sentiments were the order of the day.

Where the French revolutionaries had their declaration of the rights of man, the English paid more attention to Goethe's romantic and Rousseauesque novel, The Sorrows of Young Werther, which A W von Schlegel splendidly described as "a declaration of the rights of feeling". Those English obsessions, decorum and tradition, began to look destined for the lumber-room of history.

In 1798, under the imprint of a minor provincial publisher, a slender volume of poetry was published with no author's name on the cover and the unassuming title, Lyrical Ballads, with a few other poems. Twenty years later it was recognised as the point of ignition for English literature's revolution of sensibility.

The great critic William Hazlitt looked back on 1798 as an epoch in his life. In a vivid essay called "My first acquaintance with poets", he remembered the privilege of meeting the two authors of those Lyrical Ballads, the as yet little-known William Wordsworth and Samuel Taylor Coleridge. They read aloud some of the poems in the collection - "The Thorn", "The Mad Mother", the "Complaint of a poor Indian woman" - and, in Hazlitt's words:

The sense of a new style and a new spirit in poetry came over me. It had to me something of the effect that arises from the turning up of the fresh soil, or of the first welcome breath of Spring.

The literary establishment did not share Hazlitt's enthusiasm. The reception of Lyrical Ballads was initially lukewarm. Wordsworth was frustrated. His purposes had not been understood. So it was that in 1800, when the collection was reissued together with a second volume of new poems, he wrote a long preface. It was his manifesto for the new poetry of feeling.

His aim in the poems, he said, had been to explore "the manner in which we associate ideas in a state of excitement," to examine how human beings behave at times of extreme emotional stress.

In particular, he had sought to tap into some of the fundamental passions which the urbane and polished poetry of the previous century had all too often neglected. The "maternal passion", for instance - the subject of "The Idiot Boy" and "The Mad Mother". Then there was "The struggles of a human being at the approach of death", as in "The forsaken Indian woman". And "the perplexity and obscurity which in childhood attend our notion of death, or rather our utter inability to admit that notion".

This last idea is wonderfully conveyed by the ballad "We are seven", in which an adult confronts a little girl, one of a family of seven children, two of whom have died. To the calculating adult, "If two are in the churchyard laid, / Then ye are only five," but to the child who sits and sings to her siblings in the grave, there is no acknowledgement of death: "Nay, we are seven!"

Motherhood, children, death. Wordsworth saw that to bring the three together would be to open the floodgates of feeling. And to do that would return poetry to its primal source, for, in the preface's most famous phrase, "all good poetry is the spontaneous overflow of powerful feelings".

Among the most peculiarly haunting of the 1798 Lyrical Ballads is "The Idiot Boy". This must be the first poem in any language on the subject of a Down's syndrome child. It is at once touching, funny and just a little holy. It says something about the special grace of both handicapped children and those who care for them.

Returning to the Wordsworth of 1798 at the end of 1997, you find yourself thinking of all those images of Diana with the damaged children. You find yourself thinking of mothers, of death, of licensed tears. There was a "spontaneous overflow of powerful feelings" on the streets of London in the first week of September, and only the most cynical - the most Wildean - of commentators can deny that a deep sincerity pervaded the assembled mass. "The idea of sincerity," wrote the critic Lionel Trilling, "can never be far from our thoughts when we speak of either Rousseau or Wordsworth."

In trying to express their feelings for Diana, an extraordinary number of people reached for poetry. Message upon message at the gates of Kensington Palace was laid out in the form of verse.

Many of these verses were prepared with great care on home computers, double-spaced, centred, lineated with the blank spaces that differentiate poetry from prose. The cumulative effect was to endorse the preface to Lyrical Ballads when it argued that "the deeper passions" and poetry were proved to have a natural connection.

Metrical arrangement, however rudimentary, was the means of both expressing and ordering all those strong but inchoate emotions stirred by the death of the princess. As Wordsworth put it:

"The music of harmonious metrical language, the sense of difficulty overcome, and the blind association of pleasure which has been previously received from works of rhyme or metre of the same or similar construction, all these imperceptibly make up a complex feeling of delight, which is of the most important use in tempering the painful feeling which will always be found intermingled with powerful descriptions of the deeper passions."

Not all poetry, however, is good poetry. Had Wordsworth been transported through time from the Westminster Bridge where he once stood to the Kensington Palace green of September 1997, he would have been saddened by the cliche- ridden language in which most of the epitaphs were written. The versifiers of the greetings card industry have much to answer for.

Wordsworth's constant aim was to escape received "poetic diction" and to root out all "falsehood of description". True poetry, he argued, came from simplicity and sincerity. The language of good poetry is no different from that of good prose. The gaudy phraseology and figures of speech traditionally associated with poetry choke the true voice of feeling.

A small suggestion for those planning memorials to Diana: take note of the Wordsworthian principles. "I have at all times endeavoured to look steadily at my subject," he wrote in the preface. What he discovered from his steady gaze on death and loss and pain was that sincerity needs simplicity.

Jonathan Bate is the author of `The Genius of Shakespeare' (Picador). `The Cure for Love', his novel about William Hazlitt, will be published in the spring