A story about Donald Knuth

Donald Knuth's son taught math at my high school. Another teacher once related the following story about him:

Donald Knuth sat down to write a book, but he found that he was having too many thoughts. He started to write them down one by one, and then using a shorthand, but he found that even then he still couldn't write them down quickly enough. So he just wrote down the first letter of each thought. After filling up pages and pages with letters, he went back and wrote the book from these notes.