Cyril Connolly described it as 'something between a work of art and a case history' but William Hazlitt's Liber Amoris feels much more like the latter. If it has attracted attention over the years, it's because other people's love affairs are so enthralling, espedally when they link a famous author to a teenage 'mystery'. As the classic mid-life crisis, this one has been anatomized by some of the finest brains in Britain and, as always, the experts disagree. Was Sarah Walker an angel or a slut, or a little bit of both? And was Hazlitt an ugly, awkward scribbler or a fascinating older man?

Mr Walker was a tailor; his wife ran a boarding house between Staple Inn and Chancery Lane. He was quiet and respected but a little dull, while she was noisy and vulgar. She took in legal gentlemen and had recently married her eldest daughter Martha to one of them, a banker's son. Her youngest (Betsy) would also marry well in due course. A knight's son in her case. Sarah, the middle one, was proving more difficult.

Hazlitt (42) met Sarah (19) when she took up breakfast on 16 August 1820. (He had the two back rooms on the second floor, looking towards Lincoln's Inn Fields Hazlitt was immediately struck by her silent grace - she glided rather than walked and her movements with the tray reminded him of some religious ritual. Not a word was spoken but as she left the ...