 Within The New Yorker 's pages , Spiegelman contributed strips such as a collaboration titled " In the Dumps " with children 's illustrator Maurice Sendak and an obituary to Charles M. Schulz titled " Abstract Thought is a Warm Puppy " . An essay he had published there on Jack Cole , the creator of Plastic Man , called " Forms Stretched to their Limits " was to form the basis for a book in 2001 about Cole called Jack Cole and Plastic Man : Forms Stretched to their Limits . 
