More than 60 years ago, a New York editor named Margaret Anderson received a manuscript entitled “Thoughts on the Nature of Mass Movements.” The second paragraph of the preface announced its theme:

“All mass movements generate in their adherents a readiness to die and a proclivity for united action; all of them, irrespective of the doctrine they preach and the program they project, breed fanaticism, enthusiasm, fervent hope, hatred and intolerance; all of them are capable of releasing a powerful flow of activity in certain departments of life; all of them demand blind faith and singlehearted allegiance.

“All movements, however different in doctrine and aspiration, draw their early adherents from the same types of humanity; they all appeal to the same types of mind.”

Being a trade editor, Anderson realized that “Thoughts on the Nature of Mass Movements” wasn’t likely to jump onto any bestseller lists. So she suggested a new, punchier title, which was accepted by its author, the virtually unknown Eric Hoffer. Since then “The True Believer” has become a modern classic, a work periodically rediscovered to this day, most recently in the aftermath of the 9/11 terrorist attacks.

Eric Hoffer was, if anything, even more remarkable than his book. When “The True Believer” was published in 1951, he was a largely self-educated longshoremen, aged 50 or thereabouts (there is doubt about his actual birth date), a barrel-chested guy who earned his living by loading and unloading ships on the docks of San Francisco. Close up, Hoffer was genially round-faced, bald, with big hands, seldom going outside without a cloth cap on his head. He lived by himself in a single room, owned next to nothing except his work clothes, some writing supplies and a library card. When he spoke, he revealed a slight German accent and a marked tendency to grow excited about ideas.

In the museum world, there is a category called “outsider art,” that is, painting and sculpture created by untrained “folk” artists. Hoffer practiced what one might call “outsider philosophy.” He simply followed his own lights, his own intelligence.

As Tom Bethell’s fine critical biography, “Eric Hoffer: The Longshoreman Philosopher,” reminds us, Hoffer loved this country fiercely and was deeply proud to be an ordinary American workingman. Throughout his adult life, though, he devoured serious books, copied out favorite passages from his reading onto index cards, and thought hard about the nature of man as a social, political and religious being. By the time of his death in 1983, he had 11 titles to his credit, including “The Passionate State of Mind,” “The Ordeal of Change” and a “best-of” collection called “Between the Devil and the Dragon.”

While Hoffer excelled at the short essay and aphorism, he really shone in discussion: The veteran newscaster Eric Sevareid called his hour-long CBS interview with Hoffer “the greatest filmed monologue I had ever had anything to do with in all my years in television.” Still, this “longshoreman philosopher” was primarily a reactive thinker, usually developing his own train of thought by building on, or contradicting, observations from earlier writers. Bethell devotes an entire chapter to examples of Hoffer’s reading notes.