“There’s an old saying that great writing is simple but not easy, and so it is. The search for that one plain but inobvious word that will do the work of five, the agony of untangling a complex idea that has become a mass of phrases in the writer’s mind, the willingness to keep doing it over and over and over again until it is right — all of that plus some luck yields prose so clear that it seems a child could have written it.”

That’s William Souder writing about the author and conservationist Rachel Carson in his 2012 biography “On a Farther Shore.” It also nicely describes the work of biographer Souder himself: painstakingly researched, psychologically nuanced, unshowy, lucid.

He is drawn in subject to American originals whose lives are marked by great success, self-doubt, and an eerie capacity and need for solitude. A fascination with and absorption in nature characterize Carson and the ornithologist and painter John James Audubon, the focus of Souder’s 2005 Pulitzer Prize finalist “Under a Wild Sky.”

In his newest biography, the smart, soulful and panoramic “Mad at the World,” Souder has chosen a subject on the same continuum: John Steinbeck, another loner who, like Audubon and Carson, refined his craft through mature, dogged, self-punishing industry.

A key connecting thread between Souder’s last book and the current one is the marine biologist Ed Ricketts, who was a literary model for Carson, a best friend and onetime co-author with Steinbeck, and the inspiration for the character Doc in Steinbeck’s 1945 novel “Cannery Row.” Steinbeck and Ricketts collaborated on “Sea of Cortez,” a 1941 chronicle — as hedonistic as scientific — of a voyage in the Gulf of California to collect marine specimens. One can easily imagine Souder deep into his research on Carson, becoming smitten with the Monterey mystique around Steinbeck and Ricketts, and happily awakening to his next subject.

Audubon struggled to capture some of the vast variation and abundance of American bird life. Carson sounded the alarm over the dire insecticide threat to that abundance. And Steinbeck spied a pattern that bridged nature and sociology. Assiduously trundling through the writer’s journals and letters, as well as his 33 books, Souder explains the particular importance of the “phalanx.”

“Steinbeck eventually came to believe that you could not understand humankind by looking at individuals — any more than you could interpret a human being’s behavior by looking at one of their cells,” Souder explains. “The answers were all in the phalanx, the superorganism, the group unit.” The phalanx, Steinbeck believed, is a repository of knowledge about all that humanity has endured, including, in his words, “destruction, war, migration, hatred, and fear.”

Souder delineates the centrality of that notion to Steinbeck’s storytelling. It is the magical ingredient that makes his characters gritty but also larger than life. In “The Grapes of Wrath,” after all, what are the Joad family and the greater migrant surge of Dust Bowl “Okies”? Phalanxes.

So, in a lighter vein, are the paisanos of “Tortilla Flat” (1935) and the bittersweet ragtag assortment of intellectuals, tradesmen, prostitutes and derelicts in “Cannery Row.” Steinbeck also describes what happens to those whom the societal phalanx rolls over, like the two hapless wanderers Lennie and George in the 1937 novella “Of Mice and Men.” Once Souder highlights the phalanx theme, in fact, a reader could become obsessed with it, charting it all the way to the corrupt Long Island suburbs of Steinbeck’s last novel, “The Winter of Our Discontent” (1961).

Despite fame, the glamour of movie and stage adaptations, and a fortune that somehow still always left him scrambling at tax time, Steinbeck — tall, rugged, charismatic — had trouble finding phalanxes of his own. Ricketts and the colorful crew around his Monterey, Calif., specimen lab may have been the most satisfying before Ricketts’s 1948 death in a car accident, a loss that Steinbeck took hard.

His third marriage was the charm, yet as a father he demonstrated a neglect bordering on abuse that echoed his distance from his own father, whose middle-class status was somewhat precarious and who always seemed to be at the office.

Steinbeck worked brief stints as a war correspondent in Africa and Europe during World War II and decades later, in a hawkish vein, in Vietnam. In the public’s mind, and even more so in Steinbeck’s own, Ernest Hemingway loomed large as a figure of comparison. Steinbeck might be considered a more American-centered version of Hemingway as Papa elbowed his way around the world.

Souder explores the very real possibility that their behaviors and depression as men in their 60s might have parallels as well — both likely from head trauma in their war reporting and other endeavors. “Ironically,” Souder writes, “the only time he and Steinbeck met — at a bar in New York in the spring of 1944 — Hemingway had interrupted the otherwise dull evening by breaking a walking stick over his own head to prove he could.”

Out of touch, Steinbeck endeavored to reacquaint himself with America in the charming and bogus “Travels With Charley,” an early-1960s quest, with his wife Elaine’s standard poodle, into the heartland. Published just six years before his death at age 66, the book masqueraded as reporting but was mostly another reach of the imagination. Steinbeck made the trek in defiance of doctors’ orders after recovering from what was probably a stroke. His explanation drips with droll, self-sabotaging stubbornness:

“I have always lived violently, drunk hugely, eaten too much or not at all, slept around the clock or missed two nights of sleeping, worked too hard and too long in glory, or slobbed for a time in utter laziness. I’ve lifted, pulled, chopped, climbed, made love with joy and taken my hangovers as a consequence, not as a punishment. I did not want to surrender fierceness for a small gain in yardage. My wife married a man; I saw no reason why she should inherit a baby.”

The author remained humble before the phalanx of literature, as his characters are humbled by the phalanxes of life. Asked if he deserved the 1962 Nobel Prize for literature, he responded, “Frankly, no.”

Steinbeck, of course, absolutely deserved the prize. He captured quintessentially American moments in indelible literary hues, from the demonic to the hopeless to the unstoppable. And Souder, in his own humble style, has brought a deeply human Steinbeck forth in all his flawed, melancholy, brilliant complication.

Alexander C. Kafka has written about books and the arts for The Washington Post, the Boston Globe and other publications.

Mad at the World

A Life of John Steinbeck

By William Souder

W.W. Norton. 464 pp. $32