O is for Oscar (and Ostrich feathers, Oxford and all manner of Obscenity)

To mark the 100th anniversary next month of his death, we present the A-Z of the writer, aesthete and dandy who defined decadence, declared his genius and helped invent the modern age. (No wonder they locked him up.)

A is for Aestheticism The belief that there is no higher value than beauty and that the cultivation of beautiful things and experiences is the essence of civilisation. Oscar Wilde took up the idea after moving into elegant rooms in Magdalen College, Oxford, and came to embody it. Though no oil painting, he believed that to dress, think, speak and behave with a sense of beauty was morally imperative. Later he changed his mind, and decided that beauty had nothing to do with morals. "No artist has ethical sympathies," he wrote. "An ethical sympathy in an artist is an unpardonable mannerism of style." This is one of the Aphorisms for which he is celebrated, along with "All bad art is the result of good intentions".

A is for Aestheticism The belief that there is no higher value than beauty and that the cultivation of beautiful things and experiences is the essence of civilisation. Oscar Wilde took up the idea after moving into elegant rooms in Magdalen College, Oxford, and came to embody it. Though no oil painting, he believed that to dress, think, speak and behave with a sense of beauty was morally imperative. Later he changed his mind, and decided that beauty had nothing to do with morals. "No artist has ethical sympathies," he wrote. "An ethical sympathy in an artist is an unpardonable mannerism of style." This is one of the Aphorisms for which he is celebrated, along with "All bad art is the result of good intentions".

B is for Aubrey Beardsley The former insurance clerk whose black-inked, cruel-faced, weirdly-robed and sexually on-for-it figures in the illustrations to Wilde's Salomé were the perfect expression of fin-de-siÿcle decadence. (Though Oscar went off him when he realised he was being lampooned in the features of Herod.)

C is for Cadogan Hotel At No 75 Sloane Street, London SW1, the Gethsemane-like scene of Oscar's downfall. The date was 5 April 1895. Forced to abandon his libel case against the Marquis of Queensbury, with the press gleefully reporting the sensational exchanges at the trial, Oscar was urged by friends to leave the country. Instead he havered. He went to the Cadogan (a favourite retreat, round the corner from his home in Knightsbridge) and sat all day in Room 53 drinking hock-and-seltzers with his pal Robbie Ross. The police tactfully allowed him time to catch the boat-train to France, then - when he didn't - came and arrested him. John Betjeman imagined the arresting officer's words: "Mr Woilde, we 'ave come for tew take yew/ Where felons and criminals dwell,/ We must ask you to leave with us quoietly/ For this is the Cadogan Hotel." You can still book into the notorious room (telephone 020-7235 7141), only now it's Room 118.

D is for Lord Alfred 'Bosie' Douglas Whose relationship with Wilde was disastrous but sustained to the end. Pouting, aristocratic, sulky and rude, Bosie would have benefited from a good slap early in life; but Oscar loved him. "He lies like a hyacinth on the sofa, and I worship him," he wrote to Robbie. There was, apparently, little sexual hanky-panky between them. Bosie didn't fancy the fat and increasingly puffy Wilde, patronised him as a bourgeois and wasn't keen on sodomy, anyway. But they became inseparable, hunting working-class boys as a predatory couple.

E is for The Importance of Being Earnest Generally held to be Wilde's finest play. WH Auden described it as the perfect example of a "verbal opera". (And see under O is for Oxford.) Also, for Jacob Epstein who sculpted the frieze - a flying sphinx - that looms over Wilde's tomb. The sculpture was taken to Pÿre-Lachaise cemetery, Paris in 1912, but banned as "indecent" by French authorities.

F is for William Frith Whose painting, Varnishing Day at the Royal Academy gave Wilde his iconic status as talker, thinker, explainer and hang-on-his-every-word impresario of art. In a crowded RA gallery, he is pictured, catalogue in hand, holding forth to three ladies (and, at crotch-level, a small boy) while the rest of Victorian society listens in - and four men, resplendent in whiskers and toppers, glare at his ceaseless flow of arty blather.

G is for Dorian Gray The gilded youth in Wilde's gothic/aesthetic extravaganza The Picture of Dorian Gray, who never ages, while the picture in his attic takes on all the lineaments of cruelty, selfishness and vice perpetrated by its human subject. Published in 1891, it's partly a teasing portrait of the artist as exquisite, shocking outsider ("Yet these whispered scandals only increased, in the eyes of many, his strange and dangerous charm...") and partly a protracted, mortally dull, critique of JK Huysmans' Against Nature.

H is for Merlin Holland Oscar's grandson and number one torch-bearer, who is absolutely everywhere this autumn, discussing here, chairing symposia there, interviewing actors and writers (Simon Callow, Maggi Hambling), editing De Profundis for a stage production at the Cottesloe Theatre and publishing albums of his grandpa's photographs.

I is for Ireland Where he spent the first 20 of his 46 years. At Trinity College, Dublin, he was useless at sport but a brilliant classical scholar. He met his first big influence, John Pentland Mahaffy, tutor in Greek at Trinity. And he met Edward Carson, his nemesis.

J is for Japanese china Wilde acquired it at Oxford. It was blue and white, and not terribly exciting really, but, in one inspired phrase, he used it to focus the inchoate thinking of the Aesthetic movement. He said he hoped he could live up to it.

K is for Kiss That which sealed his fate. In court, cross-examined by Edward Carson, he was doing fine until he was asked if had kissed one of a number of working-class minors. "Certainly not," he said. "He was far too ugly." Consternation. Everything went to hell shortly afterwards.

L is for Lilly Which he allegedly carried through the London streets. Actually, Wilde denied having done so, but was gratified that he'd made the world believe he had.

M is for 'Sebastian Melmoth' The nom de plume Wilde adopted on leaving Reading Gaol. It's from the novel Melmoth the Wanderer by Charles Maturin, which he revered - Maturin was his maternal great-uncle.

N is for Newdigate Prize The high-prestige Oxford poetry award Oscar won in 1879 with "Ravenna", despite its awful, glutinous iambics ("How strangely still! No sound of life or joy/ Startles the air; no laughing shepherd-boy/ Pipes on his reed, nor ever through the day/ Comes the glad sound of children at their play").

O is for Oxford Where Oscar spent four years, at Magdalen College, changing from a geeky-looking cove in a music-hall comic's hat to a floppy-haired, floppy-tied, teapot- stanced "bard of beauty" - from Stan Laurel to Hugh Grant in a few of years. Students at Magdalen are staging a "contemporary interpretation" of The Importance of Being Earnest from 25 October. In the cast, playing the Rev Chasuble, is Douglas Murray, the 20-year-old student biographer of Lord Alfred Douglas. Weird how things go round in circles, eh?

P is for 'Patience' Gilbert and Sullivan's sparkling caricature of the Aesthetic movement, in which the figure of Bunthorne (a vision in knee-breeches) is clearly Wilde and the foolish Grosvenor is probably Swinburne. It fixed in the public mind the image of the wilting, lily-sniffing ephebe, swooning with rapture at the Grosvenor Gallery. And it nailed Wilde's languid obiter dicta in two sensational lines: "You must lie upon the daisies and discourse in novel phrases of your complicated state of mind/ The meaning doesn't matter if it's only idle chatter of a transcendental kind."

Q is for the Marquess of Queensbury Inventor of the rules of boxing, father of Lord Alfred Douglas and spittle-flecked hater of Oscar Wilde for seducing his son from the path of manliness. He was, by all accounts, a nasty, crude, brutal, shouting, hard-riding, coarse and staggeringly insensitive man who once introduced his mistress to his wife and proposed they tried a threesome.

R is for Reading Gaol Where Oscar was incarcerated for two years with hard labour. The Ballad of Reading Gaol was not, as you might expect, written in the nick. Wilde began it in the village of Berneval-sur-Mer, near Dieppe, in the north of France, shortly after his release from prison in 1897. It was published under the convict nom de plume of "C.3.3.".

S is for 'Speranza' As Oscar's mother was known. Born Joan Francesca Elgee, she was built on generous lines and an impetuous, romantic nature. A Young Ireland zealot and fervent nationalist, she contributed patriotic verses to The Nation magazine, and ran a fashionable literary-political salon at No 1 Merrion Square, Dublin. She was a godawful poet, but Oscar inherited her flamboyance and her artificiality.

T is for No 16, Tite Street In Chelsea, where Wilde went to live after his marriage to Constance Lloyd. Oscar wrote at Carlyle's writing desk in a room with yellow walls and red lacquer. He bathed in an upstairs study surrounded by divans and oriental rugs. One way or another, he seems to have spent an unconscionable amount of his time horizontal.

U is for the United States Where, in 1881, he conducted the most triumphant transatlantic author tour since the heyday of Dickens, lecturing on "The English Renaissance" to Harvard students in knee-breeches and dandy velvets, and advising Californian frontier scouts on tasteful home decor.

V is for Vera Or The Nihilists, which was Oscar's first play. Set in medieval Russia, it features among the dramatis personae Tsar Ivan the Terrible and a whole garret of masked conspirators. Unfortunately, just before it was due to be staged, the non-fictional Tsar Alexander II was assas- sinated, and it was thought insensitive to the royal family to stage a drama that clearly favoured the insurgents. It was, however, produced in New York in 1883.

W is for Sir William Wilde Oscar's father. Officially the Surgeon-Oculist-in-Ordinary to Her Majesty, Queen Victoria, he was a shocking piece of work - a scruffy, hirsute, hard-drinking womaniser who fathered several illegitimate children. When one of his ex-girlfriends turned on him and attacked him in letters and public pamphlets, Sir William found himself in court during a libel case, accused of rape and strangulation. He elected not to appear in the witness box. This spooky foreshadowing of later events happened when Oscar was 10.

X is for X-rated Rehearsals of the London production of Salomé in 1891 were halted when the Lord Chamberlain's office banned the play. Not because it was decadent, but because some forgotten statute prohibited the representation of Biblical characters on the English stage. Also for the infamous eXplosion of diarrhoea with which Wilde ended his life, 100 years ago on 30 November.

Y is for Yellow Book The "Illustrated Quarterly" that epitomised the soul of the 1890s, from its sickly cover tint to the short-lived reign of its first art director, Aubrey Beardsley. Amazingly, Wilde never had anything published in it; he was shut out by the dual animosity of Beardsley and the editor John Lane (who published Salomé).

Z is for the Zeitgeist Which Wilde embodied - the fag-end of Victorianism, the fascination with surfaces, the institutionalised hypocrisy, the capacity for outrage. Wilde revelled in his wider identity, even though it destroyed him in the end. "I was a man who stood in symbolic relations to the art and culture of my age," he wrote in De Profundis. "I treated Art as the supreme reality, and life as a mere mode of fiction. I awoke the imagination of my century so that it created myths and legend around me. I summed up all systems in a phrase, and all existence in an epigram."