One afternoon in June 1995, I found myself trapped in the Bodhi Tree, a stucco-fronted bookstore on Melrose Avenue in West Hollywood where New Age wisdom-seekers sip herbal tea while discussing the latest ravings of Shirley MacLaine. I was freaking out because the professor I’d travelled 6,000 miles to meet had apparently stood me up. Stephen O’Leary, of the University of Southern California, had just published Arguing the Apocalypse, a prize-winning study of the rhetorical techniques of televangelists. I was researching my own book about the end of the world and was desperate to pick his brains. He was almost two hours late and the wind chimes were driving me nuts.

I liked to snack on benzodiazepines, which I always think go nicely with Californian sunsets

I was seriously considering flying back to London when this tubby little bearded guy scuttled in, babbling excuses and making a squeaky fuss about the best place to sit on the veranda. He wore shorts and Birkenstocks. Then he launched into his Aristotelian theory of millennial rhetoric, speaking so fast that he lost me in seconds. We’re not going to hit it off, I thought, not realising that my life had changed forever.

Ten years later I paid him another visit and O’Leary was still babbling – about Plato, The Simpsons, Karajan’s first Beethoven cycle and the intricacies of the Mayan calendar. That sounds like a mess, but Stephen made it hang together because he was the cleverest person I’d ever met. Also, we were high. We were staying in a scummy Mexican seaside resort famous for its dodgy pharmacies and we were on a mission. We had a shopping list of interesting prescription drugs. Stephen scored some Ritalin he needed in order to finish a paper about premillennial dispensationalism. Or so he claimed.

Back in his apartment in LA, I had some tedious indexing to do. Stephen was out teaching his class. Where had he put the Ritalin? When he got back there was an explosion: ‘You ate the whole pack, you greedy bastard!’ But, hey, the index was finished, and I didn’t feel guilty because the year before Stephen had promised to send me some delicious Adderall through the post; he even meticulously concealed the pills in the spine of an ancient copy of William James’s The Varieties of Religious Experience. Then he tore it open and scoffed the lot himself.

Every trip to see Stephen was like Fear and Loathing in Las Vegas for nerds. He kept moving apartments. Each was messier than the last. In the early years there were fragile shards of coloured glasses stacked in the backyard. His hobby was melting them into gorgeous windows; he made one that still hangs in his Harvard dormitory building. Eventually he couldn’t be bothered. That was a bad sign.

Thank God I gave up alcohol before I met Stephen. But I liked to snack on benzodiazepines, which I always think go nicely with Californian sunsets, and that suited him just fine. It meant I kept quiet while he dropped the needle on Keith Jarrett’s Sun Bear Concerts and then talked over the music, guzzling bourbon as he eviscerated the theories of Carl Gustav Jung. This was a guy who had absorbed the canon of western literature while he was a teenager – and got busted for selling grass. That schoolboy naughtiness was hard-wired into him: we once crashed a seminar in a Pall Mall club and no one noticed the bottle of sauvignon vanishing into the professor’s overcoat.

This was a guy who had absorbed the canon of western literature – and got busted for selling grass

But naughtiness is one thing; addiction is another. When I first met Stephen he lived in a house, not an apartment, with an adorable family. It’s hard to think fondly of him when you know what he put them through. But finally, one of the rehab sessions seemed to have worked. He rediscovered his passion for the ‘joyful hollering’ of shape-note singing, a musical genre unknown outside America. In the 19th century, Protestant settlers loved to sit opposite each other and bawl out hymns; these days Christians and secular folklorists keep the flame burning, producing what Stephen’s friend Jim Friedrich, an Episcopal priest, describes as ‘a volcanic eruption of sound that blasts and sears you like heat from a forge’. No wonder Stephen relished it; his own bathroom arias had us all begging for mercy.

At the beginning of 2020 Stephen rang to tell me he’d been diagnosed with cancer of the colon – but he didn’t want me to overreact. He knew the chemo would be horrible, and the doctors didn’t think he could be cured, but that was OK because death would be ‘interesting’. Was he serious? I didn’t press him, because that was his business and in any case I was exhausted from the daily challenge of not saying the wrong thing to my younger sister, whose cancer was definitely terminal but who banned all mention of death.

And Stephen, bless him, worked out that I was shipwrecked with depression; it preyed on his mind and later that week he wrote me what I can only describe as a platonic love letter. His basic message was to get out of bed and take exercise because it was my duty to regain the capacity to feel pleasure. ‘And if you cannot imagine feeling such pleasure now, then, if nothing else, remember the mutual pleasure that you and I once enjoyed when we sat together and talked far into the night, while we shared the music of Bach and Beethoven and Palestrina and Byrd and Tallis. I cannot imagine a world without you in it, a world in which such pleasures are lost to me for ever… Ask for help, and help will come. And even when I cannot be there with you, I will always be there for you.’

I wonder what he meant by ‘always’. A few days later, on 24 January, a heart attack spared Stephen the horrors of chemotherapy. Every year I grieve for him on his anniversary. There’s no danger that I’ll forget. Why was I in the Bodhi Tree all those years ago? Because I wanted to meet the world’s greatest expert on apocalyptic calendars, who never failed to derive amusement from their coincidences and ironies. So it seems fitting, somehow, that he brought our rollercoaster of a friendship to an end by dying on my birthday.