On or off stage, dancers always seem to hold their bodies in that instantly recognizably trained posture: heads held high, backs straight, no trace of a slouch. They look as though they’re being pulled gently upward by an invisible force, even when doing the most quotidian tasks. That hard-to-emulate quality — the very antithesis of the hunched-over pose we adopt while squinting into our smartphones — is probably best defined as “grace.”

We increasingly rely on gadgets that distance us from others and funnel our attention into an almost entirely cerebral experience, at the expense of our ability to navigate and respond to the physical world (to wit, the dangers of texting while doing anything else). But there may yet be hope for us slouchers and squinters. Sarah L. Kaufman’s new book, “The Art of Grace: On Moving Well Through Life,” makes the case that the quality of grace is not really about perfection, nor is it simply the absence of clumsiness, but rather a Bruce Lee-like ability to respond to the unexpected with equanimity.

Kaufman, a Pulitzer Prize-winning dance critic at The Washington Post, has spent more than two decades immersed in the world of choreographed elegance on stage. Thus, it makes sense for her to take a deep dive into the subject of gracefulness, which she unpacks historically and artistically. The sublimely elegant Cary Grant, who moved fluidly and had a knack for making others comfortable, is her conceptual North Star.

“The Art of Grace” has two major points to make: The first is that grace is ultimately the quality of being at ease in one’s own skin, whether one is a lithe ballerina, a powerful athlete or simply an ordinary person out doing errands who remembers to hold the door for someone. It’s about a kind of physical empathy, knowing where one is in space and in relation to other people and, most of all, understanding how our actions and presence affect those around us.

The second point is that while we tend to associate the word “graciousness” with pearls, fish forks and people such as Jacqueline Kennedy Onassis, grace is in fact “wonderfully democratic”; that is, it need not be genteel to be genuine. Kaufman’s definition of the word makes it available to all, even the ungainly among us. “Grace is the transference of ease from one body to another,” she writes. “When we witness grace, we feel that ease echo in our own bodies.”

Sarah L. Kaufman suggests in her new book that the baby boomer generation has derailed etiquette — and the grace that goes with it. (Deb Lindsey)

Not surprisingly, Kaufman’s deft way with words aligns perfectly with her subject: Smooth and controlled, she writes with authority about an impressive array of subjects and only occasionally betrays an amusing flash of “kids today” curmudgeonliness. She mines history’s etiquette books, including the 4,500-year-old “Maxims of Ptah-Hotep,” written by an adviser to the pharaoh, whose instructions to his son about how one should comport himself in society comprise what scholars believe might be the world’s oldest book.

Most of the 16 chapters of Kaufman’s book are devoted to the manifestation of grace in particular fields: hospitality, politics, sports, dance, art, theater — she even finds examples of grace in the physically demanding and fast-paced work of cooks, waiters and strippers. This juxtaposition of the glamourous and the workaday stakes a democratic, almost craftsman-like claim for grace, decoupling it from social class and repositioning it as something that can be worked at and perfected rather than nonchalantly inherited.

While her profiles are fascinating (the subjects include Nelson Mandela and Margot Fonteyn), the section that really gives this book its spine, and a few choice barbs, is “Grace and the Art of Getting Along: How the Baby Boomers Derailed Centuries of Manners Instruction.” It is here, woven together with a discussion of historical etiquette manuals, from the writings of 16th-century Florentine poet and archbishop Giovanni Della Casa to the advice of Emily Post and Ladies Home Journal, that Kaufman diagnoses our own era as “the grace gap.”

The sins of the grace-gap generation are myriad, and, in many cases, technology colludes to magnify the irritation factor. Kaufman’s examples include minor instances, such as “manspreading” on the subway and the more serious lack of accommodation for the elderly, poor and unemployed. She interviews Miss Manners herself, Judith Martin, who comes to the defense of little white lies, although pointing out that because they grease the gears of social interaction, good manners are also, in the strictest sense, open to accusations of fakery or lack of sincerity. This has made traditional etiquette a target for the generation that raised its kids on “Free to Be . . . You and Me.” Citing research that narcissism and lack of empathy are on the rise among the selfie generation, Kaufman argues convincingly that something has been lost along the way.

“Just be yourself,” the rallying cry of the post-etiquette set, may be a good method of avoiding artifice and the anxiety of putting on a stiff, polite persona, but the focus is on the wrong person: Rather than me, it should be you. The essence of etiquette and grace is the focusing of one’s attention on someone else. Will the person next to me on the subway mind if I stretch my legs out as far as they can go? Probably. Will I bump into someone if I text as I walk down the street? There’s a good chance I will. Rather than imposing a strict set of rules, Kaufman argues that cultivating an awareness of how our physical selves affect those around us is crucial to getting along and adapting in a frenetic world.

This chapter alone could be expanded into a book. There are times, in fact, when the scope of “The Art of Grace” almost feels too broad, and with so many examples of how grace manifests itself — physically, psychologically, politically, artistically — the argument can seem a bit strained. Still, the connections Kaufman draws between seemingly unrelated fields are thoughtful and inspiring.

Sarah Archer is a writer on the arts who lives in Philadelphia.

On Friday, Nov. 20 at 7 p.m., Sarah L. Kaufman will be at Barnes & Noble, 4801 Bethesda Ave., Bethesda, Md.

On Moving Well Through Life

By Sarah L. Kaufman

Norton. 310 pp. $24.95