A cute book, both text and illustrations are worthwhile, and William Steig did both. He was in his sixties when he decided to start writing books for kids. This was his third one, and is often considered to be his best. It won the 1970 Caldecott Medal, and so far has sold over 500,000 copies.
thanks to:
http://www.williamsteig.com/williamsteig.htm
http://www.bookpage.com/9908bp/childrens/sylvester.html
www.amazon.com