I'm afraid Mr Philip Hensher rather let his misogyny get the better of him in his recent review of Hermione Lee's new biography of Virginia Woolf in the Spectator. Although, poor dear, one can understand he was under some strain, since reading the book has clearly been a long exercise - 900 pages - in discovering things he didn't want to know. Like what Woolf was wearing when she first met Madge Garland (something that looked like "an upturned wastepaper basket on her head"), when she had her ears pierced and "God help us, what she used for sanitary towels."

The knowledge that she "made her own out of kapok" is going to give me a new slant on the author of Mrs Dalloway and To The Lighthouse - quite apart from the fact that I thought kapok was the crumbly, sponge-like material sometimes used to stuff sofas. "God help us," cries Hensher in that histrionic, goaded-beyond- endurance way. Apparently the self-obsessed old cow wrote about all this in her diary, which he describes, piquantly, as "going on for page after page about herself". This seems as nimble a definition of a diary as any. If it comes to unsavoury detail, I happen to know what Joe Orton washed his penis with after anal sex*, but alien to my nature though this might be, I don't get grossed out over it. This detail is gleaned from Joe Orton's entertaining diary, in which he goes on for page after page about himself - though I dare say Orton's tales of oral sex with dwarves in the pissoirs of the Holloway Road are more congenial to Mr Hensher than women's menstrual arrangements. Orton's journal, let us not forget, was called, with the delightful reticence that was such a hallmark of his character, Diary of a Somebody. In it we learn about the miserable life chez Joe and Kenneth: the interminable rows, numbed sex sessions and dinners of tinned mashed salmon, and it is all fascinating.

Pepys would be an example, I suppose, of a diary that didn't "go on and on" about its owner, but we are all Post-Romantics now and burbling obsessively about our feelings is unavoidable. I began my diary at the age of 11 in the Pepysian mode: got up, went to school, fell over in playground, ate my tea. My own Romantic revolution occurred about the age of 17, after which not a fact could be gleaned from the narrative, so awash was it in subjectivity; large stream-of-consciousness stretches even now resemble Ginny W at her most febrile. "Yes, but did I ever even kiss X?" I think now as I skim its ink-stiffened pages (one of the most curious things about diaries are the way they get visibly thicker with the weight of all those words). "Was that the last time I met Y? And what the hell was I going on about there?"

It seems unreasonable to convict Woolf of self-obsession on the grounds that she kept a diary. You would have to assume she intended it to be published. Anyway, writing at great, moaning length in a private diary is considerably less egotistical than boring your friends with your problems. Self-therapy can keep those around you sane. Sometimes you're simply saying: "I was here, I lived, this proves it." This seems not so much egotism as a basic human need.

Even the most self-obsessed journal can throw up nuggets of brilliance. Sylvia Plath's passionate neurosis frequently attains the status of black comedy. Quite often, Plath has heavy colds. And she has periods. Quite often the heavy colds and the periods coincide. Then the misery reaches a crescendo that can only make one thankful for not being a genius. I suppose only a uniquely self-obsessed and self-adoring person would write about having, when heavily pregnant, "a laborious goat-shit" but isn't that a wonderful, vivid, funny image?

I had to undergo a crash-course in contemporary women's fiction for my recent stint at the Dartington literary festival, and trawled up: Georgina Hammick's description of the contents of a woman's chamber pot tinged pink; Helen Dunmore's pre-WWI teenage heroine sending her rusty bundle of rags to be washed by the maid; and Julie Myerson's female protagonist going to see her secret lover shortly after giving birth. He fumbles for her but she backs off; she's wearing "maternity pants ... with a pad". "For God's sake," you can imagine Mr Hensher reeling back in revulsion at all this talk of stitches, and blood, and oozing nipples; but I must say I rejoiced in this infinitely tender, touching detail. Perhaps this is what women's writing is all about.

* Dettol in a bucket of water. For God's sake!