“‘For his seventh birthday, Gaiman received C. S. Lewis’s The Chronicles of Narnia series. He later recalled that “I admired his use of parenthetical statements to the reader, where he would just talk to you…I’d think, “Oh, my gosh, that is so cool! I want to do that! When I become an author, I want to be able to do things in parentheses.” I liked the power of putting things in brackets.'”
(Biography Today. Detroit, Michigan: Omnigraphics. 2010. pp. 90–91. ISBN 978-0-7808-1058-7. Cited by Wikipedia, Neil Gaiman entry).