I help him get ready for bed — “de-sock” him, fill his water bottle, bring him his sleeping tablets, make sure he has something to read.

I: “What else can I do for you?”

O: “Exist.”

Why don’t these lines resonate with romantic tawdriness? Is it because it’s an exchange between two men, and as much as we have been allowed to peep into gay sex, we have rarely witnessed gay romance? Or do these lines ring deep because O here is Oliver Sacks, the renowned neurologist and author?

The I is writer, photographer Bill Hayes. Hayes first met Sacks in 2008, after he wrote to him about his book, The Anatomist . But it was only in 2009, following the sudden death of his long-term boyfriend, and the thought of continuing to live in San Francisco became unbearable that Hayes moved to New York City, where he picked up on the thread of friendship with Sacks and, eventually became more than just a friend. In Sacks’s memoir, On the Move , published in 2015 just before his death, he reveals that when he met Hayes he had been celibate for nearly 35 years.

To be clear though, Sacks is not the centrifugal force around which Hayes’s book, Insomniac City , revolves. That honour goes to New York, as the subtitle of the book says — New York, Oliver and Me. It’s a bit of a multimedia smorgasbord; part memoir, part photo-book on the city and part inside-view of the life of a famous, but more importantly, complicated man. In many ways, the answer to my original question is none of the above. Hayes is the kind of man, certainly the kind of writer, who can easily imbue a warm fuzziness to any encounter. This is at once the best and the worst part of Insomniac City .

“I moved to New York eight years ago and felt at once at home,” Hayes starts the book. And every encounter he has in the city is etched in a golden glow. Vagabond poets, taxi drivers, the man who runs the newspaper kiosk, all become characters through whom Hayes understands and appreciates New York. All of these vignettes — and here I must admit that I am often the most cynical person in any room, yet even to me — seem to come etched in a golden sunshine of friendship, hope and generosity. Despite how far Hayes takes some of his statements — “Garbage overflows from trash cans. The air stinks. But there is a warm pinkish glow from the setting sun. Gorgeousness” — he makes them seem truthful, or at the very least, genuine. He seems to be one of those escapees from a Californian meditation centre, eternally focused on the bright side, forever seeing silver linings. And yes, this can get a bit tedious, but it never feels like a lie.

The photographs in the book — regular people from regular New York streets — and the staccato nature of sentences and chapters, make the book seem like a long stroll through someone’s wall on Facebook or timeline on Twitter. Yet, it works. It allows the reader a casual intimacy with Hayes, a quick way to see things from his point of view, in fact often through his viewfinder.

Endearing as this is, it is intimacy of another kind that makes the book a winner. Hayes writes with such tenderness about Sacks, describing the mundane and the profound with such simplicity, that even at an age like mine, all you can do is surrender to the force of an unusually pure kind of love. Sacks is, mentally, both a genius and a child. And Hayes sketches his delightful character by merely reporting on their conversations, not editorialising them.

“1-11-10:

O: “Everyday, a word surprises me.”

**

7-10-10

O: “I’ve suddenly realized what you mean to me: You create the need which you fill, the hunger you sate. Like Jesus. And Kierkegaard. And smoked trout…”

I: That’s the most romantic thing anyone has ever said to me — I think.”

Later: I thought he was gazing at me lovingly as I drove, but then realized, no:

“I am watching the odometer and thinking of the elements,” says O

**

1-1-12

Just before midnight, I taught O how to open a bottle of champagne, something he had never done before: sweet to see the joy and surprise and fear on his face as — pop ! — the cork exploded. He had insisted on wearing his swimming goggles, though, just in case.

**

Undated note — June 2011:

The difference between us in two words:

“Me, too,” I say.

“I, too,” O corrects.”

What can I say? In these times of public lynchings and private abuse, Insomnaic City is salve for the soul.