Our first imperative was to eliminate “clutter,” which Bill regarded as “the disease of American writing.” Photograph by Walter Daran/The LIFE Picture Collection/Getty

Our revelatory encounters with teachers who will make a difference in our lives stay with us as vividly, I think, as our recollections of falling in love. In college, I had two such experiences.

The first occurred in the fall of my freshman year at Yale, in 1968. I’d been placed in a mid-level, rather than entry-level, English poetry course by virtue of a misleadingly respectable score on the SAT verbal, the result of compulsive memorization of vocabulary and word-analogy lists in a Barron’s test-preparation workbook. A month into the term, the professor, Charles Long, gently but firmly explained that he didn’t expect me to offer novel insights into “The Faerie Queen” or “Paradise Lost.” More urgent, he wanted me to recognize that I had no clue how to write an essay. That fall and winter, Long forbearingly shepherded me through rewrites of the papers he assigned, and incrementally I started to get the hang of it. By spring, though I barely knew what to make of “The Love Song of J. Alfred Prufrock,” my freshman English-essay bullshit had begun to approximate the B.S. of classmates who’d prepped at institutions more exacting than my public high school in Oklahoma.

Three years later, I wangled a spot in “Nonfiction Workshop,” a class taught by William Zinsser, a New York City newspaperman turned freelance magazine writer who had reinvented himself as a teacher of writing. Robert Penn Warren and John Hersey then famously taught oversubscribed fiction-writing seminars under the aegis of the exalted Yale English department because . . . well, Warren, Hersey, fame, and fiction. “Nonfiction,” though, had an unseemly utilitarian ring. (Trade school? Here, call the number on this matchbook.)

What Bill Zinsser had to offer was unlike anything else in the Yale course catalogue. He had arrived in 1970, not as an academic appointee but at the invitation of the critic R. W. B. Lewis, the master of Calhoun College, one of the (then) twelve undergraduate residential communities. Fortuitously, as he recalled in his book “Writing Places,” the managing editor of the Yale Alumni Magazine had several months earlier taken up with the wife of the editor (ah, the seventies!), and all parties had rusticated to distant Zip Codes. So, despite no previous connection to the university, Bill had also been hired to edit the magazine.

Officially, “Nonfiction Workshop” was a residential-college seminar, independent of the English department or any other department. Before long, word got around about this cheerful fellow Zinsser, not another eyebrow-arching pipe smoker in an elbow-patched tweed jacket but a real professional craftsman who had sneaked in the side entrance of the academy from the real world. Actually, Bill did own a tweed jacket (or maybe it was polished twill), and he favored button-down shirts, narrow neckties, unfancy shoes, and unironic hats (felt Borsalino or straw Panama). He wore glasses and was slightly built, a pleasant-looking, engaging, well-mannered optimist steeped in the tribal codes of privileged Wasp self-effacement.

We met for two hours every Thursday afternoon in a comfortably furnished lounge in Calhoun College. In that room, we mostly listened, as Bill read, along with examples from his own work, passages from writers I’d read but hadn’t properly considered (Thoreau, Orwell, Twain, E. B. White, Red Smith), or knew of but hadn’t much read (Mencken, Perelman, Wills, Didion, Talese). Some I already revered for their supreme coolness (Norman Mailer, Hunter Thompson, Tom Wolfe). Others, previously unknown to me (Alan Moorehead, Michael Arlen, Joseph Mitchell), proved to be more enduring influences.

The weekly writing assignments—thousand-word limit, a safeguard for Bill’s sanity—required us to try our hands at a wide range of forms: humor, interviewing, travel, science, sports, criticism, editorials. This regimen inevitably yielded the occasional face-first failure, soon to be transmuted by pedagogical alchemy into an edifying failure. At the end of class, Bill would return our papers from the previous week, each illuminated with his editing suggestions and provocative marginalia. I still wince at his dead-on appraisal of my travel piece: “You’ll notice that I stopped marking this halfway through. What you’ve written is interesting only to you.”

Our first imperative was to eliminate “clutter,” which Bill regarded as “the disease of American writing . . . unnecessary words, circular constructions, pompous frills, and meaningless jargon.” After forty years at The New Yorker, I would never suggest that his standards exceeded those of scores of incisive and vigilant editors who have saved me from mortification. I do know that it’s taken me more than an hour to solve this paragraph. Throughout, I’ve been conscious of his voice while refining my own—instinctively applying Zinsserian admonitions, pruning the verbiage, savoring the luxury (to paraphrase Twain) of finding the right word rather than settling for the almost right.

In 1999, twenty years after Bill left Yale and moved back to Manhattan, I sent a group letter to his former students, encouraging them to write about their experiences in “Nonfiction Workshop,” for inclusion in an archive at New York University’s Fales Library, where he had donated his papers. There seemed to be two schools of thought about what color ink Bill used when he cut us down to size. One woman wrote, “William Zinsser’s writing seminar was a humbling experience for me. I remember the ferocity and sting of his red pen.” Another maintained that he once told her class, “I never use red pen to correct. It always looks like the page is bleeding.” Blood turned out to be a pervasive motif: “No one has ever attacked my work with a blue pencil like Bill Zinsser. I watched essays swagger into class like General Custer, only to find themselves cut to shreds and shot full of holes, bleeding on the prairie, wondering where their first three paragraphs had gone. For sloppy, spongy, timid writing, Bill Zinsser’s class was the Battle of Bull Run.” This came from someone who took the course the same term I did, in the fall of 1971. I knew him as Jeff Stuart Goldfarb. Evidently, he took so seriously Bill’s exhortations to eliminate clutter that he had his last name legally blue-penciled and is now simply Jeff Stuart. If he would only work harder, he could be Jeff.

Bill wrote nineteen books—among them “American Places” (travel), “Spring Training” (baseball), “Willie and Dwike” (the jazz musicians Willie Ruff and Dwike Mitchell), “Easy to Remember” (the American songbook), and, most memorably, “On Writing Well,” published in 1976, which captured “Nonfiction Workshop” between hard covers. Now in its seventh edition, it has sold more than a million and a half copies. Teaching became Bill’s secular ministry, and he never stopped. For many years, he gave a course in memoir-writing at the New School. He coached entering students at the Columbia Graduate School of Journalism. He accepted invitations for teaching gigs of varying duration, all over the country. His phone number was listed, and when strangers called with writing questions, he listened and did what he could to help.

Though in otherwise fine health, in late middle age he began having trouble with his eyes. The first insult was a detached retina, followed twenty or so years later by glaucoma, which progressively made the daily commute from his apartment, in the East Sixties, to his office in the East Fifties, an uncertain undertaking. In 2010, he proposed writing a weekly essay for the Web site of The American Scholar. Like most eighty-seven-year-olds, Bill did not aspire to digital mastery: he never had an e-mail address; until he started writing a blog, he’d never read one. This deterred neither him nor The American Scholar’s editor, Robert Wilson. (“How could we not say yes?”) The blog—Zinsser on Friday, seven hundred words a week—ran for nineteen months, until his dwindling eyesight forced him to give it up. He closed his office at the end of 2011. His final book, “The Writer Who Stayed” (Paul Dry Books), a collection of selected columns, was published the following year. Meanwhile, The American Scholar had nominated Zinsser on Friday for a 2012 National Magazine Award for digital commentary. Of course, he won. Robert Wilson graciously allowed him to bring home the miniature Alexander Calder copper stabile, the “Elephant.” It rested conspicuously on a square white table in the center of his living room. By then, however, he couldn’t see it, or anything else.