I’ve been meaning to look up who Dr. Seuss actually was, after all the Cat in the Hat reading over the last few years! According to Wikipedia, he was Theodor Seuss Geisel, an American born in 1904, who died in 1991 – an artist, carttonist and writer.
Here’s how The Cat in the Hat came about…
In May 1954, Life magazine published a report on illiteracy among school children, which concluded that children were not learning to read because their books were boring. Accordingly, William Ellsworth Spaulding, the director of the education division at Houghton Mifflin who later became its Chairman, compiled a list of 348 words he felt were important for first-graders to recognize and asked Geisel to cut the list to 250 words and write a book using only those words. Spaulding challenged Geisel to “bring back a book children can’t put down.” 
Nine months later, Geisel, using 236 of the words given to him, completed The Cat in the Hat. It was described as a tour de force by some reviewers[who?]-—it retained the drawing style, verse rhythms, and all the imaginative power of Geisel’s earlier works, but because of its simplified vocabulary could be read by beginning readers. The Cat in the Hat and subsequent books written for young children achieved significant international success and they remain very popular today. In 2009 Green Eggs and Ham sold 540,366 copies, The Cat in the Hat sold 452,258 copies, and One Fish Two Fish Red Fish Blue Fish (1960) sold 409,068 copies—outselling the majority of newly published children’s books.