Theodor Seuss Geisel, who was called Ted as a boy but would one day be known to the world as Dr. Seuss, was born in Springfield, Massachusetts, in 1904. His father, Theodor Robert Geisel, who co-owned a brewery, often took young Ted to the city zoo. Perhaps inspired by these visits, Ted — with the encouragement of his mother, Henrietta Seuss — drew animal caricatures on his bedroom walls.

In 1921, along with 16 fellow graduates of Springfield’s Central High School, Geisel enrolled at Dartmouth College in New Hampshire. He was immediately attracted to the college humor magazine, “Jack-o-Lantern,” and began contributing stories and cartoons to it, becoming its editor-in-chief in his junior year. It was in the magazine’s pages that he first used the pseudonym “Seuss,” after an infraction of the law got him deposed as editor.

Geisel went on to a career in advertising in New York city, creating illustrations for an insect spray and other products. His first appearance between hard covers came in 1931: a series of illustrations for a book called “Boners,” filled with unintentionally funny excerpts from school tests and term papers. The first Dr. Seuss book, “And to Think That I Saw It on Mulberry Street,” came six years later.

Click here for 30 things you didn’t know about Dr. Seuss.

Dr. Seuss produced some 66 books in all, counting those he wrote but didn’t illustrate, those he co-authored or wrote under a pseudonym, and those that were published posthumously. He is the world’s best-selling children’s author, and according to some sources either the ninth or 11th most popular fiction writer of any kind in history, beating out Stephen King, Leo Tolstoy, and many other famous authors of past and present. His books, which have been translated into 30 languages, have sold somewhere between 500 million and 650 million copies.

The book that made Dr. Seuss a star was his 13th, “The Cat in the Hat,” published in 1957. It came about as a reaction to an article in LIFE magazine bemoaning the state of children’s reading levels in America. Geisel’s publisher asked him to write a book using only 220 basic vocabulary words so it could be used as a children’s reader. “The Cat in the Hat” was the result (he actually used 236 words, but nobody complained), and it became a hit immediately.

The book’s success inspired him and his publisher to launch a whole series of Beginner Books, written by Dr. Seuss and others. In the early 1950s, he had also started to produce books with allegorical social or political messages. For instance, “Horton Hears a Who!” stands against prejudice; “Yertle the Turtle” is about the overthrow of a dictatorial turtle said to have been based on Adolf Hitler; “The Sneetches” opposes anti-Semitism. Later, he also published “The Lorax,” a plea for environmental conservation, and “The Butter Battle Book,” which tackles the theme of nuclear disarmament.

Variously hailed as the American Poet Laureate of Nonsense and the Modern Mother Goose, Dr. Seuss has brought pleasure to (and encouraged reading comprehension in) four generations of children around the world. But not everything about him was family-friendly. 24/7 Wall St. has uncovered some surprising facts about this prolific author and illustrator.

Methodology

To unearth little-known facts about Theodor “Dr. Seuss” Geisel, 24/7 Wall St. consulted the Springfield Museums’ Seuss in Springfield website, Penguin Random House’s Seussville website, the website of the New England Historical Society, an article reproducing early Seuss cartoons on Buzzfeed, and the following books: “Dr. Seuss: The Cat Behind the Hat” by Caroline M. Smith; “Of Sneetches and Whos and the Good Dr. Seuss,” edited by Thomas Fensch; “Dr. Seuss & Mr. Geisel: A Biography” by Judith & Neil Morgan; “Theodor Geisel: A Portrait of the Man Who Became Dr. Seuss” by Donald E. Pease; “Who Was Dr. Seuss?” by Janet B. Pascal; and “The Beginnings of Dr. Seuss: An Informal Reminiscence,” edited by Edward Connery Lathem.