Mary Martin as Peter Pan, 1954 illustration by Al Hirschfeld. ( The Hirschfeld Foundation)

The Hollywood director Billy Wilder once famously said, “If you’re going to tell people the truth, be funny or they’ll kill you.” Al Hirschfeld would have put it the other way around: If you are going to poke fun at people, make it the gentle truth.

For almost a century this astonishing artist bent his nimble pen to recording the frauds, fools, flops and hits of the American stage and screen, the passing spectacle and its backstage realities, a world he became a part of yet never ceased to record at a certain distance with a wondering but undeceived eye. He was at his desk every morning, and he created an estimated 10,000 drawings in his lifetime. He began work at 19 and was still at it when he died at the age of 99.

Who can forget his sketch of a grinning Mary Martin, flying through the air as Peter Pan, as if she could do it every day (and did)? What about Irving Berlin at the piano, having just turned, eyebrows afloat, to accept the adoration of his public? Then there was Harold Ross, the famously difficult editor of the New Yorker, whose photograph Hirschfeld doctored in a series called “Photo Doodles” for Life magazine, adding a mustache and pointy eyebrows that make Ross look like Stalin. How about Katharine Hepburn as Coco Chanel, ribbons and bows aflutter as she glares down her tiny nose in icy disapproval? Hirschfeld saw it all.

Born in St. Louis, Hirschfeld was one of three boys whose father “was not regularly employed,” as David Leopold tactfully puts it, and whose mother ran a store to make ends meet. Hirschfeld drew from childhood and took some classes at the National Academy of Design after the family moved to New York City, but was never subjected to an academic rigor, which perhaps helps to account for his idiosyncratic style and perennial inventiveness.

In 1924, when he was just 21, he was already established as a brilliant illustrator, playing with styles and techniques as easily as he would do with caricature. At the beginning, his caricatures verged on the radical — a block of wood for a head — but soon they eased into the suppler, more fluid and confident style of his mature work.

"The Hirschfeld Century: Portrait of an Artist and His Age" by Al Hirschfeld, edited with text by David Leopold. (Knopf)

Hirschfeld’s particular gift for the eye-catching poster was evident almost at once. He designed one for the film “Hallelujah” that takes a daring diagonal, in red, black and gold. His many posters for Buster Keaton movies include a brilliant one for “Sidewalks of New York.” And in his advertisements for the comic team of Laurel and Hardy, he accentuated their contrasting physiques (the gaunt Laurel, the roly-poly Hardy) by thinking of them as forming the number 10.

In the 1930s and ’40s, more and more work came in partly because, as Hirschfeld once observed, there is plenty of talent in the world but not always a zeal for continual self-application. His creations began to appear in newspapers, magazines and theater programs, and on billboards and murals. He married, had a baby girl (the Nina whose name her father was to imbed in so many of his later drawings) and went on living the precarious life of a freelancer. The precariousness ended in 1948 after he and the humorist S. J. Perelman concocted a book, “Westward Ha!”, which became a bestseller. He also became a regular contributor to the New York Times. For the first time, the Hirschfeld family had a modicum of security, as well as a town house in New York. One of the notable caricatures of that period was of Charles de Gaulle. This proud and forbidding figure, under the amused gaze of Hirschfeld, displays sagging eyes, a tiny button mouth and the mournful gaze of a hungry turtle.

The 1950s were a great period for Hirschfeld, a decade of one thrilling production after another, a postwar release of vitality that brought with it the pulsing beat of “The Pajama Game” and the sad-eyed mastery of Bert Lahr in “Waiting for Godot.” Many talents — Fred Allen, Mike Todd, Mae West and Milton Berle among them — caught Hirschfeld’s eye as they lunched at the Stage Deli.

One of the book’s pleasures is its liberal use of color, along with plenty of white space: It is an instant classic. Among its treasures one finds the famous poster for “My Fair Lady” in which George Bernard Shaw, author of the play “Pygmalion” (on which the musical is based), looms above it as master puppeteer. For economy of means nothing can beat Hirschfeld’s depiction of jazz musician Lionel Hampton in full flight on the xylophone, his lower regions transformed into a keyboard. Then there is a wonderful self-portrait. Hirschfeld sits, preparing for work, dipping his pen into the top of his head, which has become a handy inkwell. A fountain of inspiration indeed.

In later years, Hirschfeld drew a caricature of playwright Arthur Miller at age 80. Miller once said of him: “People in a Hirschfeld drawing all share the one quality of energetic joy in life they wish they had in reality. . . . He makes us all seem like . . . a merry band of vagabonds whose worst features he has redeemed.”

For Hirschfeld it was a perfect epitaph.

Meryle Secrest is a biographer who writes frequently about art and artists.

Portrait of an Artist and His Age

Edited by David Leopold

Knopf. 320 pp. $40