Happy Centennial Dr. Seuss!!:
"Geisel had a contract to write a children's book. The purpose of the book, initially, was to build and rehearse early reading vocabulary. He was told that he could write whatever he wanted so long as he only used words from a list of some 250 very simple words. That was it. He could not use any word that was not on that 250 word list. Well, he kept getting stuck, starting a story line using words on the list and then finding himself unable to advance the story or even back out of the plot because he would have to use a word not on the list. Eventually, he switched strategies. He stopped thinking in terms of plots and characters and started with the words themselves, finding rhymes and rhythmic combinations and playing with associative linguistic slides from one word set to another. "