The Cat in the Hat of all time. As of 2007, more than 10 million copies of "The Cat in the Hat" have been printed, and it has been translated into more than 12 different languages, including Latin, under the title "Cattus Petasatus". In 2007, on the occasion of the book's fiftieth anniversary, Random House released "The Annotated Cat: Under the Hats of Seuss and His Cats", which includes both "The Cat in the Hat" and its sequel, with annotations and an introduction by Philip Nel. The book was published to immediate critical acclaim. Some reviewers praised the book as an exciting way to learn
The Cat in the Hat read, and Spaulding provided Geisel with a similar list. Geisel later told biographers Judith and Neil Morgan that Spaulding had supplied him with a list of 348 words that every six-year-old should know and insisted that the book's vocabulary be limited to 225 words. However, according to Philip Nel, Geisel gave varying numbers in interviews from 1964 to 1969. He variously claimed that he could use between 200 and 250 words from a list of between 300 and 400; the finished book contains 236 different words. Geisel gave varying accounts of how he conceived of "The Cat in the Hat".