"Flash of Two Worlds!" is a landmark comic book story that was published in The Flash #123 (Sept. 1961). It introduces Earth-Two, and more generally the concept of the multiverse, to DC Comics. The story was written by Gardner Fox under the editorial guidance of Julius Schwartz (whose subsequent autobiography was titled Man of Two Worlds), and illustrated by Carmine Infantino. In 2009, DC Comics released a new digitally remastered graphic novel collection, DC Comics Classics Library: The Flash of Two Worlds. It features the classic flagship story and other subsequent pre-Crisis Flash material. Source: Wikipedia (en)