There are classics of childhood that get the easy mention, the legacy slots in the literature canon: Here we have Laura Ingalls, Anne of Green Gables, Billy Coleman and his coon hounds in “Where the Red Fern Grows.” And there are understated classics that elbow their way more subtly into beloved literature, wildly popular but still deeply personal — books that read like a private letter to every reader. Meg Murry (“A Wrinkle in Time”) lives in this category, and so does Claudia Kincaid.

Forty-odd years before Ben Stiller spent a night at the museum, Claudia Kincaid did it first, at the Met, with her kid brother Jamie, in “From the Mixed-Up Files of Mrs. Basil E. Frankweiler.” E.L. Konigsburg, who wrote that book, died on Friday in Falls Church, Va. at age 83. She wrote 20 other books and won two Newbery Medals (and one Newbery Honor — in 1968 she lost to herself), but Claudia was her ur-heroine, the gloriously competent 12-year-old who orchestrated the most fantastical run-away: sleeping in historic beds, scrounging for money in fountains, skulking in bathrooms to avoid security guards.

And what else was it about? Oh, everything. About familial relationships, and sibling rivalry, and money management, and batty old women driving Rolls Royces. And it was, more than anything, a celebration of nerdery, decades before geekdom became a badge of honor. Armed with cash and train passes, Claudia and Jamie could have gorged on candy and roller coasters, or holed up for weeks sneaking into R-rated movies. Instead they spent their days taking museum tours, and unraveling a centuries-old art mystery. Instead they read books on Michelangelo, and used their remaining funds to travel to Connecticut and dig through someone’s disorganized card catalog. (Prompting Mrs. Frankweiler, the owner of the catalog, to instruct her attorney to re-draft her will.)

The unspoken message — appropriate, considering that Konigsburg’s early career was spent as a science teacher — was that learning was cool. And being into something was cool. And hanging out with your little brother, and doing all pre-teendom’s typically mockable activities — those things were cool, too. At the end of the book, Claudia and Jamie learned the secret of the Michelangelo sculpture. But they don’t tell anyone. Because knowledge is worth possessing, even when it’s not publicized, even when it’s not Tweeted. It carries its own inherent worth.

Konigsburg’s last book, written in 2007, was called “The Mysterious Edge of the Heroic World,” about a sixth grade boy on a journey to discover something “no one else knows.” I haven’t read it. I can’t wait to. I hope the hero discovers what readers of Konigsburg have known for a long time: It is possible for something to feel like it belongs to just one person, while secretly belonging to us all.