Claire McCardell, the midcentury designer who is one of the founding mothers of American sportswear, did many things first.

She was the first designer to put pockets in a dress that wasn’t for housecleaning. The first to embrace the capsule wardrobe, to use gingham for evening wear and denim for day dresses, to popularize the ballet flat, to put her name on her label.

And she was one of the first to put her philosophy of dress down on paper, offering up what may still be the best how-to book on navigating a wardrobe that has been written.

Titled “What Shall I Wear?” and originally published in 1956, the slim volume has now been reissued in a new edition by Abrams with a foreword by Tory Burch, who has made it her mission to give Ms. McCardell’s name the same status as Saint Laurent in the popular imagination. (Ms. Burch has also created a fellowship dedicated to Ms. McCardell’s work at the Maryland Center for History and Culture in Baltimore, where the McCardell archive resides.)

And though Ms. McCardell’s work is also having something of a moment thanks to the Metropolitan Museum’s current American fashion extravaganza, which highlights often overlooked but important American designers (mostly women and designers of color), the book offers proof of concept in an entirely more accessible, contemporary kind of a way.

Indeed, in an era that has seen a proliferation of branded glossy coffee-table tomes, not to mention endless dress advice from influencers on TikTok and YouTube, it may prove the essential text for anyone struggling with the basic question of what to wear to go back to work or school — or for anyone getting up in the morning and staring morosely into their closet.

That’s not just because much of the advice within is witty, though it is, or because there are practical suggestions for how to shop and pointed meditations on the importance of comfortable shoes and investment dressing. But because Ms. McCardell focuses on prioritizing the individual, rather than the industry. Also, she’s as good at aphorisms as Diana Vreeland, fashion’s most famous deliverer of one-liners, though Ms. McCardell’s have more functional application.

Consider, for example, a few choice excerpts: “If fashion seems to be saying something that isn’t right for you, ignore it.” “If you are smart you will forget labels and look for fine lines.” Also my personal favorite: “Your job is not so much tracking down the clothes as tracking down yourself.”

Too true.

Ms. McCardell didn’t drink the Champagne of fashion; she remixed it. It’s this attitude that comes through in her book — and it was in her clothes. That, as much as anything, was integral in defining the difference between American style, with its emphasis on utility and ease, and the more top-down, dictatorial European style. And that still resonates today.

As Ms. McCardell wrote, “I prefer to think of sports clothes as uninfluenced by Paris — clothes that wield their own influence.” Clothes that were influencers, in other words, before influencers. Though influencers themselves could learn something from the book.

The only time the text seems arcane is when it gets mired in the gender politics of its era. These days, “You will be in the spotlight at eight o’clock when you drive your husband to the train and go on to do the marketing,” can be a little hard to swallow. Update the words to “You will be in the spotlight at eight o’clock when you get on the train and go on to work,” however, and they become entirely relevant.

In a new afterword to the book, Allison Tolman, the vice president for collections and interpretation for the Maryland Center, posits that the wifey asides were the work of Edith Heal, Ms. McCardell’s ghostwriter, trying to filter the designer’s palpably independent leanings through a more broadly palatable 1950s lens. This may be true; Ms. Heal’s other work included “The Young Executive’s Wife: You and Your Husband’s Job.” Either way, it’s not enough to detract from the charm and currency of Ms. McCardell’s book.

Besides, “What Shall I Wear?” is, it turns out, part of another fashion trend, one in which designers are becoming vocal book boosters themselves.

Alongside Ms. Burch, peers who have found inspiration in the printed page include Kim Jones of Fendi and Dior Men’s, who is a compulsive vintage book collector (he has more than 20,000 volumes) and whose first Fendi collection was an ode to the Bloomsbury set. Add on the list: Joseph Altuzarra, who teamed up with Penguin Classics during the height of the pandemic and has been handing out famous tomes like “The Odyssey” and “Moby Dick” stuffed with fabric swatches as the literary equivalent of mood boards ever since.

Also, Pierpaolo Piccioli of Valentino, who last year supported nine independent book stores in the United States with an ad campaign based entirely on narrative text to evoke ideas and emotion, rather than clothes. And Matthieu Blazy of Bottega Veneta, who will be collaborating with The Strand bookstore during this season’s New York Fashion Week, curating reading lists of his favorite books and designing a trio of special tote bags.

Mr. Blazy called The Strand “almost a motif that recurs throughout my life.”

It is, he said, always his first stop in New York City. “It always reaffirms to me why physical books are so important,” he said. “It’s always a space of exploration with the constant pleasure of the unexpected and finding something new.”

There’s something about a book’s materiality and authorial style that finds common cause with the catwalk. If in doubt, simply spend some time with Ms. McCardell, whose advice accessorizes the mind, not just the house — and costs less, these days, than the price of a tube of haute lipstick.