The last time I visited my parents, I borrowed a novel from the shelves in my old bedroom. Once, the books there belonged to me, but in the decades since I lived in this apartment, my father has commandeered the space.

It’s only fitting. The two of us have always communicated through our libraries. For us, this represents a love language of sorts.

I grew up in a house full of books, and from an early age I had permission to look at anything. The only rule was that I had to return it when I was done.

That’s harder now than it was when I was younger. My parents live, as they have for more than 50 years, in Manhattan, and I decamped for Los Angeles years ago. Both are in their 80s and need assistance. They have in-home care, and we in the family check on them frequently.

The book I grabbed was S.A. Cosby’s 2019 debut novel, “My Darkest Prayer,” a bleakly pointed piece of Southern noir. At first, I was a bit surprised my father had heard of Cosby. And yet the more I thought about it: Why not?

For as long as I’ve known him, he has kept index cards with lists of titles. He has an account at his neighborhood bookstore. They know him and recognize his tastes. When he was younger, he used to say he wouldn’t mind aging as long as he could read. Even now, I often find him with a book, although I fear he has begun to fall out of the narrative.

That’s the reason I picked up “My Darkest Prayer” — I wanted to stay close to him. Throughout my life, the most deeply shared moments between us have taken place when we were reading in the same room, each enmeshed in a book, aware the other is doing the same. We don’t have to talk.

It’s a strange intimacy, reading. We’re still and silent as we animate stories in our minds. I’ve never felt as rooted or as safe as I have in such a circumstance. This I learned from my father.

I didn’t read “My Darkest Prayer” until I was back in Southern California. I didn’t want my father to know I had the book. I didn’t want him to know I had the book because I didn’t want him to feel any pressure to discuss it. I didn’t want to know what he might or might not recall.

The two of us have been talking books ever since I read his copy of Frederick Forsyth’s “The Day of the Jackal” when I was 12. Together we’ve encountered Trevanian and Michael Crichton, Percival Everett and Philip Roth. That our tastes, our passions, don’t always overlap is part of the dynamic. He loves le Carré. I have little use for espionage. And I have never managed to tilt him Faulkner’s way.

I wasn’t thinking about any of that, exactly, when I took up Cosby’s novel, and I wasn’t thinking about it as I read into his world. What I discovered, however, was an unexpected double vision: I was aware not only of the narrative firing my imagination but also of the physical volume in my hands.

My father has never been a collector, really. He doesn’t care about first editions. He simply likes to read. But he is as proprietary about his books as he is about shelf space. He has always marked them, initially with ex libris stickers and now by imprinting his last name — in capital letters — into the cover with a hand-held metal press. When he is done, he folds a deep crease into the front of the book, right beside the spine.

I prefer a neutral approach: neither breaking the spines nor marking the pages. I used to write my name inside my books. I don’t do that anymore.

With “My Darkest Prayer,” however, I wanted the crease in the cover. I wanted my father’s mark. Opening the book felt like opening a conversation between us. It felt like entering his mind. I wanted to retrace his steps, his thinking. I wanted to read through his eyes. As I stepped into the story, I could almost feel my father on the same path.

It called to mind the loose ritual we had fallen into last summer, on one of my visits to New York. Each morning, he would start a crossword puzzle and I would finish it, correcting his miscues and filling in the remaining squares. Then, as now, I didn’t say anything. It felt as if we were meeting in the grid.

On the morning he completed an entire corner of the quadrant, I felt as proud as a parent, but mostly I was looking for a gentler intervention: to ease myself into his language, and in so doing to find a way to him.

In the end, I enjoyed Cosby’s novel, although that’s neither here nor there. I was most struck by a plotline in which the narrator mourns his parents, a process I am already coming to know.

When I was done with “My Darkest Prayer,” I ran my fingers over my father’s mark, those letters he’d pressed into the cover, spelling out a name the same as mine. Then I slipped the book into my suitcase, so I’d be certain to return it, the next time I visit, to the shelves in my old room.