For more than 40 years, Hortense Calisher’s pen has served as a scalpel slicing through to the emotional underside of American life and quietly, deftly laying bare its inevitable inconsistencies, its fears and its small triumphs.

Now, aged 75, after 15 novels and a well-received autobiography (Herself) that have placed her firmly in the pantheon of nonblockbuster literary gods who can be depended on for a steady stream of solid craftsmanship, she has written what appears to be a coda—the chronicle of a septuagenarian architect and her husband, a minor poet, whose legacy to each other is an almanac to be read only after one of them dies.

That is no easy task, yet Calisher makes of the archive a gently lyrical paean to the intelligent examination of lives lived well together. It is wry, annoyed, bittersweet, ever open to the surprises of daily life that seem destined to remain with us regardless of age and experience. And it is erotic. Yes, erotic. Old couples who have enjoyed many years together (and anyone who has heard stories of the frisky flirtatiousness that attends social functions in old peoples’ homes) know that there can be another, deeper dimension to physical love.

Calisher’s aging couple have seen it all: children, survival of broken marriages that remain surprisingly well remembered if at times unreal, personal animosities that simply refuse to die. They can still be silly, and they have learned to live with regret—though never entirely. After 35 years, “What bothers us deepest,” the wife, Gemma, reflects, “is that one of us will inevitably be left behind.”

“Dear Rupert,” she taps out on her computer screen, “I write as we agreed. I begin. But I refuse to think of you as possibly to die—or dead.” There is about all this the rustle of old age, like autumn leaves pressed into the pages of a long-forgotten book. But the account is repeatedly and abruptly rescued from tedium by wordplay; for example, Gemma’s conclusion that Op-art resembles nothing so much as “a paramecium in drag.”

Such one-liners aside, Age is studded with observations about features in the landscape of the elderly. Women have surrendered to old age when they let their stockings droop. A touch or look can stir ancient memories; a word, ancient enmities. Life’s most important moments are interrupted by the need to go to the bathroom. The slump of a shoulder, a momentary memory loss—all these take on new and added meaning.

Authors long have been fascinated by the challenge of dealing acutely with the passage of time. There is a clear line connecting them at whatever level—from, say, Montaigne’s essays about the woes of gallstones and the foibles of men to Avery Corman’s new “50,” in which generational differences become dishearteningly clear in something as simple as a younger woman’s inability to hum a few bars from “Stardust.”

Calisher took up the challenge four decades ago. In prose as luminous as it is accessible, she has quested after what in an earlier book she called “the sweet kernel of the human condition.”

That is in Age. It is a quiet, well-crafted, lovely book.