I feel all kinds of stray but important connections to this book. There is no logic to them, but they seem worth recording nonetheless. There is for instance the morning I drove to meet Denise Levertov - one of the two letter-writers here - in Dublin in the mid-1980s.

It was a cold, sunshiny Irish day. She was in Dublin to give a reading; I was there to interview her for the Irish Times. I drove to a house in Rathmines: a narrow cottage that seemed to have crouched down and missed the city-wreckers and building speculators. I found her in the front room, a smiling, debonair woman, quick of speech, witty, and with an elusive air. What was it? At the time I was puzzled. Now I think, with her English birth, her American citizenship, her Russian inheritance, she was like one of those European exiles at a café table on a summer evening - able to understand every place because she had long ago lost the ability to belong to only one.

The expatriate friendliness, the ease in several worlds was characteristic of Denise Levertov. But it concealed something else: a fierce sense of poetic tribe, an outsider's need to have a community of aesthetics. If she had lost a sense of country, she could still have one of cabal. That morning in Dublin she spoke of the Black Mountain School of poetry, with which she had had an involvement in the Fifties, ...