Burglar, ghost, fiend, poet, drunk and hero

He rolled his great eyes round and round as he read his poems, looking like the mythical dog with eyes like saucers" - one of many recollections that capture the essential eccentricity of William Empson, one of the greatest poet-critics of the 20th century, in the first volume of John Haffenden's new biography.

Empson spoke out against corporal punishment while at Winchester College (where he was known as Woggy); caning was a recreation among the masters, two beatings being the minimum qualification for "a true Wykehamist". The second master, A.T.P. Williams, had a cane called "Little Willy". None of this prevented Empson from emerging as one of Winchester's best mathematicians, and he went on to read the subject at Cambridge University, changing in his final year to read English literature. His university contemporaries were among the first to recognise his talents - a distinguished generation that included Jacob Bronowski, Humphrey Jennings, Alistair Cooke, Michael Redgrave and Kathleen Raine. Haffenden includes the story of how Ludwig Wittgenstein pestered F.R. Leavis to explain one of Empson's poems. Leavis got so bogged down in it that Wittgenstein interrupted, saying: "It's perfectly plain you don't understand the poem in the least. Give me the book."

Empson was becoming known for his criticism; the great work of his Cambridge years, Seven Types of Ambiguity , remains his best-known book and deservedly so. Haffenden describes the background to it in detail, showing how it reacted to the work of Empson's tutor, I. A. Richards, and borrowed from Robert Graves.

It was not for nothing that Cooke found Empson and his circle "terrifyingly highbrow", an impression ratified by Haffenden's account of their suffocating competitiveness, not to mention their unhealthily repressed sex drives. Rampantly bisexual, Empson was less repressed than most: the discovery of a condom in his possession led to expulsion from Magdalene College. Not content merely with sending him down, the governing body stripped him of his fellowship and removed his name from the college records, destroying even his tutorial file. "As far as Magdalene was concerned, it should be as if he had never been there." They were still living in the 19th century. According to Haffenden, the master "had to have explained to him what the condoms were for", while one of the fellows was heard to exclaim: "We can't have muckers like that in this society!" Empson was probably fortunate to escape when he did, though that is not how he saw it at the time. He left with the reputation of a sex fiend, which he did little to shake off. When interviewed for a job at Birmingham University, he told the head of department he had just read "the most wonderful book" - Bronislaw Malinowski's The Sexual Life of Savages . Needless to say, it did not matter that this was a serious work of anthropological research - it was enough to scare the university off.

The most interesting part of this biography is its second half, dealing with Empson's teaching career in Asia. His time in Japan was less comfortable and productive than that in China. On his first night in Tokyo he broke into a hotel in search of food, drink and tobacco. "Once caught, it was not a burglar but a university professor!" exclaimed the local paper. His drinking continued and (still investigating what Haffenden calls "the divergent inclinations of his sexuality") he made a drunken pass at a taxi-driver, his excuse being that "the Japanese men and women look so alike that I made a mistake". Haffenden believes Empson was "looking for trouble, as if he needed a periodic crisis to relieve himself of nervous strain". Shortly after, he left the country.

"I am coming to China like a ghost," Empson told those who met him in August 1937 when he arrived in Peking, recently occupied by the Japanese as a spoil of the Sino-Japanese war. It was at this point that he seems to have found a cause: his work as a university teacher in China was nothing short of heroic. The complex political situation, in which the Nationalist and Communist Chinese were at odds while fighting the Japanese, meant that resources were scarce and conditions primitive. It would have been easier for Empson to have fled the country like other Europeans, but he stayed for two years, sleeping on his blackboard (or under it when inebriated). Bombed by the Japanese during the day, the makeshift campus of the exiled Temporary University came to life in early morning and late afternoon. He would teach his students from memory, typing out literary works for them in the absence of textbooks. It was an extraordinary experience that turned him into a charismatic and gifted teacher, inspiring many of his students to become teachers themselves; one of Haffenden's most impressive achievements is to have spoken to so many of them.

Indeed, Haffenden is never less than thorough in his assembly of witnesses, the main narrative being supplemented by copious annotations detailing his sources, some of which amount to fascinating mini-essays on aspects of the life. Not everyone will find such an uncompromisingly scholarly treatment easy to digest, and it does make for a lengthy read. Despite its amounting to nearly 700 pages, some may be alarmed to find that it gets no further than 1939. And there are times when even the most dogged Empsonian might wish for more perspective, the evidence often being presented in close-up.

That said, biographies demand to be tailored to their subjects, and Empson's is an unusual case. It is not just that he crossed paths (and swords) with other people well known in their own right - encounters that have to be unpicked with care - but that his engagement with Japan and China at crucial moments in their histories compels Haffenden to range across several disciplines at once, not something to be done in a hurry. He rises to these challenges with ease: what his admirable book lacks in narrative momentum, it gains in analytical expertise.

Duncan Wu is professor of English language and literature, Oxford University.