Inward talking

Although she began her writing life as a novelist (and wanted to be remembered for her novels), it was her non-fiction that made her name. Her many essays and monographs – On Photography, Illness As Metaphor, Against Interpretation – established her as serious thinker about art, culture and society, and her philosophical journalism, such as Trip To Hanoi, which recorded her impressions of the Vietnam War, made her a formidable member of the counter-culture movement (from which she nevertheless kept her distance).

How much then does this volume of notes contribute to her reputation or our understanding of the workings of her mind? Sontag was bisexual, and most of the notes about relationships in this volume refer to her liaisons with women. Her son David, from her eight-year marriage to Philip Rieff, has edited her work with love and honesty. Controversial statements about the rape of a friend, for example, when she asked whether the attack had "excited her sexually" and records that her friend answered "yes" are included. Yet Sontag herself wrote in 1975: "I am an adversarial writer, a polemical writer. I wrote to support what is attacked ..." which suggests the importance of making statements designed to be inflammatory.

What this volume offers is a sense of a woman talking to herself. The boundaries between public and private are constantly blurred in these 'diaries'. There are statements that sound like public pronouncements ("Common sense is always wrong. It is the demagoguery of the bourgeois ideal") and those that whisper of self-doubt, as when she had been diagnosed with cancer for the first time ("I'm safe, yes, but I'm getting even weaker. I have more and more difficulty being alone, even for a few hours").

It's not just that she "moves between different worlds", as her son suggests in his introduction, writing about Vietnam, making lists of her favourite books of the year or recording quotations from everyone from Tolstoy to de Sade to Marx. She moves between her private world, where she records her feelings of anxieties about a lover, and her public world, where her opinions count. There is surprisingly little tension between these two realms. That is indicated best, perhaps, when one entry in 1966 records her worry that she is "too 'close' to David [her young son] in the sense that I identify with him. When I spend a great deal of time with him, I lose the sense of my age ... I must learn to be alone." This is written, she also notes, "in the lobby of the Ambassador [Hotel] ... watching other people in the lobby, on the terrace ..."

No secret writing place for this diarist, no hiding her writing from prying eyes. Perhaps not unsurprisingly, Jane Austen doesn't feature on her lists, not even when she talks about 19th-century novelists and their morality plays ("Problem of writing a novel now," she notes, "no story seems that important to tell"). Sontag's ambitions are public and grand, and chime with a new century. Like Sylvia Plath, she chides herself for not being good enough and sets out "to be noble-minded. To be profound. Never to be 'nice'." To be 'nice' is to be feminine, and to be feminine is to be weak".

Her death in 2004 robbed us of a female thinker who courted controversy without becoming an object of derision the way Camille Paglia has, for instance, or being viewed as a hypocrite or liar, as have some male thinkers such as Sartre. Her reputation may have suffered from time to time, but she will surely be one of the few 20th-century thinkers to still be read 100 years from now.