The opening of another summer reading season is a time to hope, from within a hammock or beach chair, for a book that will charm us once again with the power of the written word.

But how much of what we read, even the good stuff, drops from memory soon after we close the book?

I wondered this recently after I came across a copy of Edward Hoagland’s “The Tugman’s Passage” at a rummage sale and snatched it up. I’ve followed Hoagland’s nature writing for years, so I welcomed the chance to read more of his work.

But on the drive home, a faint feeling of déjà vu began to unsettle me. Hadn’t I already read this book? Soon, a quick scan of my living room bookshelf revealed my first copy of “The Tugman’s Passage,” its pages dog-eared to bookmark choice passages.

I was shocked that a once-cherished volume had slipped so conclusively from my consciousness. Revisiting pages I’d once identified as memorable, I registered not the slightest trace of recognition.

It’s not because Hoagland’s prose is forgettable — or that it should be. At any rate, he’s in great company. A few years ago, I was at the cash register with a copy of “Speak, Memory,” Vladimir Nabokov’s classic memoir, when I remembered that I had already bought the book and read it in another season of my life. But my impressions of what was inside “Speak, Memory” spoke not a syllable, rendered mute by the march of time.

Maybe none of this should surprise me. After several decades of reading, perhaps it is inevitable that at least some of the poetry and prose that has been crammed into my brain will simply fall out, as lost to the world as the loose change beneath a sofa cushion. Socrates warned us about all of this when he cautioned that relying on text would lead to poor memory.

And isn’t that the main reason that we keep copies of books in the first place — as keepers of truth that we cannot reliably recollect? I am heartened, too, by the sizable number of books on my shelf that have lingered vividly in my awareness for years, even decades.

Yet my increasingly frequent encounters with what others have called biblio-amnesia bother me. Every time I open a book, I hope to be changed by what I read, the experience written into my DNA with indelible clarity. If so much of the work of great literary masters can travel through my senses and leave no permanent mark, what good is reading?

Maybe the best reading is the kind that merely sets the stage for rereading, so that the greatest books, like the best friends, become part of us only through regular and repeated intimacy.

Poet Mary Ruefle mentions the challenge in “Someone Reading a Book Is a Sign of Order in the World,” an essay in “Lit From Within,” a new anthology about writing that I’ve just read and, blessedly, have not yet forgotten. Ruefle estimates that she’s read about 2,400 books in her life, although she quickly confesses that “I probably remember 200, or 8 percent.” She asks herself whether, “in the allotted time left to me on earth, should I read more and more new books, or should I cease with that vain consumption — vain because it is endless — and begin to reread those books which had given me the most intense pleasure in my past, books I had all but forgotten in their details, but loved in the shadows they cast over me, the moods created by the very thoughts of them?”

I’ve been mulling this question as I enter middle age and realize that the number of summer reading seasons I’ve been given is not, alas, infinite.

I am constantly drawn to the thrill of new books, yet I’m struck by Evelyn Waugh’s celebration of rereading. “It is very pleasant losing one’s memory,” Waugh once said. “One can read old favorites with breathless curiosity.” Waugh’s remark reminds me of that old gallows humor about the virtue of senility — that one is always meeting new friends.

As this summer begins, I’ve decided to split the difference. A new edition of poet Laurie Lee’s “As I Walked Out One Midsummer Morning,” the story of his time as a young adult, is on my nightstand. But before I tackle it, I’ll spend a few hours with the book that introduced me to Lee, “Cider With Rosie,” his memoir of childhood.

It’s a book I first read several years ago.

Or, at least I think I did.

Danny Heitman, a columnist for the Baton Rouge Advocate, is the author of “A Summer of Birds: John James Audubon at Oakley House.”