I did it for a textbook house and they sent me a word list. That was due to the Dewey revolt in the twenties, in which they threw out phonics reading and went to a word recognition as if you’re reading a Chinese pictograph instead of blending sounds or different letters. I think killing phonics was one of the greatest causes of illiteracy in the country. Anyway they had it all worked out that a healthy child at the age of four can only learn so many words in a week. So there were two hundred and twenty-three words to use in this book. I read the list three times and I almost went out of my head. I said, "I’ll read it once more and if I can find two words that rhyme, that’ll be the title of my book." I found "cat" and "hat" and said, the title of my book will be The Cat in the Hat.
Dr. Seuss, 1981 Interview