Yesterday I wrote a sentence about Graham Greene in his hotel room in Tabasco crushing large beetles and reading Anthony Trollope. Today, I will get him up on a mule for a long ride across Chiapas. I will also put him on a little airplane, and  then give him a case of dysentery, for which I am sure he would be grateful.

For the last few years, I have been writing a biography of this novelist, to whom I am not related despite the coincidence of surnames. The research is finished and I am pressing forward with a possibly optimistic plan to have a draft done by next summer. My very indulgent publishers have been checking their calendars and glancing at their watches.

It is a very strange thing to inhabit another person’s life. When I was finishing my biography of Edith Sitwell (2011), I felt grief in the last hundred pages as she was now going to die. It was the completion of something that had been going on in my mind for over a decade, and I was giving that up too. You forget many of the details of the research, but you also find that an important relationship is coming to an end.

When I was in my twenties, I wrote a doctoral thesis at Oxford on the eighteenth-century poet Mary Leapor, a kitchen-maid who only lived to twenty-four, but produced some marvellous satires on the lot of women and servants — the sort of people about whom almost no information survives. Little was known about Leapor herself.  Nowadays, I am content to have my research on her plagiarized more or less constantly. She is a figure in the Norton Anthologies and plenty of other fat books, and it seems my discoveries and my claims for her importance have passed into a kind of common unfootnoted certainty.

As a graduate student, I would go into the five hundred year-old Duke Humfrey’s Library at the Bodleian — you will have seen it as the set for the forbidden books room in Harry Potter. There, with a few academical gnomes with sprouting eyebrows and tufted ears, I would root through immense county histories — trying to learn what I could from transcribed headstones. In the course of finding out about those long vanished scullery maids, ostlers, thatchers, shoemakers, weavers, farmers, you relive their deaths and lose them all over again. There are few documents as desolating as an old church register, as you become the only person in the world who knows of a life that may have lasted three days or of the young mother with whom the child was buried. You may become the only person living who knows about an epidemic that wiped out half a village.

One of my great friends, an acclaimed biographer in his 70s, often refers to the advice of Diana Athill, the 98 year-old former publisher and now memoirist, that biographies should eliminate as many names as possible. Names are hard on the reader. Athill is a wonderful figure in British letters, but I simply can’t accept the advice. Naming is a form of witness — it is all that remains of a life passed in obscurity. Mentioning that person when he or she passes through some larger narrative is the least I can do.

Like everyone else, I wonder at times about what I do in life. I love a certain number of people. I give a little encouragement here and there. I give my students some ideas to think about when they are older. But then there is the other thing. I write poems, sometimes funny, but almost always elegiac. And I write biographies. It is the attempt to understand and give value to individuals and to communities that will always be outside the normal range of seeing. It is memory as a vocation.