I first met Derek Parfit the summer I was 19, when my college boyfriend and I spent a day visiting Oxford. Parfit’s Reasons and Persons was the only thing written by a living person on our first-year philosophy syllabus at Yale. Passing All Souls College, we went to the porter’s lodge and asked, absurdly, if we could see him. The porter said Parfit was teaching a seminar in the Old Library. We stood outside the door, pressing our ears to it, hearing nothing but murmurs, debating whether or not to go in. Eventually the seminar ended and people started to file out. Realising we had no idea what Parfit looked like, we asked every man leaving the room if he was Derek Parfit. They all laughed: they must have been twenty-something graduate students. Finally, out came a man with a mane of white hair and a bright red tie tucked into his trousers, wielding a large Smirnoff vodka bottle. We introduced ourselves.

Without a trace of annoyance, Parfit signed our books and offered to show us round the college. In the 15th-century chapel he pointed out the hammer-beam roof and gilded angels, the Gothic reredos and its 19th-century statues. We talked about moral philosophy. He said he couldn’t understand why Shelly Kagan, a philosopher at Yale he deeply admired, believed in moral retribution. ‘I just can’t believe that anyone deserves to suffer,’ he said, shaking his head. After the tour he gave us detailed instructions on how to get back to the railway station, anxious that we didn’t get lost, and wished us well.

Five years later, as I was starting doctoral research at Oxford, I was elected to a prize fellowship at All Souls. Parfit – who had been a fellow there since 1967 – was appointed as my college adviser. He wrote to me suggesting we have lunch in college. Over the soup I tried to describe our first meeting, hoping that he would recall my silly earnestness and his enormous generosity. At first he seemed not to hear me. When I tried again, he changed the subject. That our lives had intersected before held no interest for him. He had simply been kind to me then, and now was kind to me again; one thing didn’t have anything to do with the other.

Instead he wanted to talk about what I intended to do with the seven years of my fellowship. He suggested I spend the first year reading novels, ‘sowing seeds’. He asked if I would like to comment on his work in progress. (The next day I received two hefty boxes of draft pages of the book that would be published in 2011 as On What Matters.) We talked about meta-ethics, and I told him I was inclined towards anti-realism, the view that moral truths are in some sense dependent on the human mind. He was visibly distressed by this – he said it implied that there was nothing wrong with torture – and I had to recant in order to stop him from leaving. After the soup was cleared we got up, and Derek took two rolls from the bread basket. He placed them on the bench where we had been sitting, to save our seats. When we returned with plates of salad he picked up the rolls and put them back in the basket.

Until his death on 1 January, Parfit was widely thought to be the most important living moral philosopher. He was loved and admired and is now mourned by even those – including me – who have a strong aversion to the kind of moral philosophy he inspired: broadly utilitarian in spirit, concerned with the maximisation of pleasure and the minimisation of pain, often indifferent to the particularity of individual persons, interpersonal relationships and human institutions. I find it hard to explain why this kind of moral philosophy, when done by Parfit, was not irksome in the way it so often is in other hands. Perhaps it has something to do with Parfit’s complete lack of smugness; one never got the sense, in his writing or in conversation, of a philosopher delighted with the reductive power of his own system. There was also his capacity for aesthetic appreciation, not just of nature (he had a particular love of bluebell woods) and architecture (he was an obsessive photographer of buildings), but of philosophy itself. Discussing in the LRB of 22 January 1998 the question of why the universe exists, he wrote:

Even if these questions could not have answers, they would still make sense, and they would still be worth considering. I am reminded here of the aesthetic category of the sublime, as applied to the highest mountains, raging oceans, the night sky, the interiors of some cathedrals, and other things that are superhuman, awesome, limitless. No question is more sublime than why there is a Universe: why there is anything rather than nothing.

Finally there was the fact that Parfit’s philosophy was a deeply personal affair. There is something odd in saying this, since he is most famous for the view that personal identity – the conditions under which you continue to exist as you – does not, contrary to appearances, really matter. We are psychological bundles of memories, inclinations, intentions. In the future there will be bundles who will go by my name, who will share many of my memories, and act on some of my intentions. They will think they are me. At a certain point – my death – there will cease to be any such bundles, though there will be other bundles who remember me and perhaps even carry on some of my projects. From this perspective, the boundaries between ourselves and others begin to dissolve. So too, perhaps, does the horror of my death. In Reasons and Persons, Parfit wrote that when he used to believe that personal identity mattered, he ‘seemed imprisoned’ in himself. ‘My life seemed like a glass tunnel,’ he wrote,

through which I was moving faster every year, and at the end of which there was darkness. When I changed my view, the walls of my glass tunnel disappeared. I now live in the open air. There is still a difference between my life and the lives of other people. But the difference is less. Other people are closer. I am less concerned about the rest of my own life, and more concerned about the lives of others.

Until a year ago, Derek read everything I wrote for publication, including my pieces for the LRB, and usually sent them back to me with detailed comments within a few hours. He would point me towards a relevant passage of Nietzsche, or suggest that a metaphor was too violent, or raise a fundamental philosophical objection. I wasn’t special to Derek; many philosophers, young and old, have similar stories. Sometimes I would pass by him in college and he would smile at me in a way that didn't entirely convince me I was recognised.

I don’t think it’s unfair to say that Derek didn’t see what is obvious to many others: that there are persons, non-fungible and non-interchangeable, whose immense particularity matters and is indeed the basis of, rather than a distraction from, morality. But in not seeing this, Derek was able to theorise with unusual, often breathtaking novelty, clarity and insight. He was also free to be, in some ways at least, better than the rest of us. After he retired from All Souls, Derek didn’t like to go to the college common room, so we had our last meeting in my study. While jostling his papers he knocked over a glass. He was unfazed. We sat and talked for a few hours, his feet in a pool of water and shattered glass.