Julius Schwartz knew that the fans hadn’t forgotten about characters like Jay Garrick or Alan Scott. But how best to acknowledge the original heroes, and have them coexist with the new identities? He had an idea, based on the parallel worlds theory. And in Flash #123, the Golden Age Flash returned in “The Flash of Two Worlds” . The story was written by Garrick co-creator Gardner Fox, and drawn by then-current Flash artist Carmine Infantino.
The story begins with Barry Allen doing a rope trick at s charity event organized by his girlfriend Iris West. While vibrating his molecules, he disappears and arrives in Keystone City, which was the home of the original Flash. (Barry’s home is Central City. When he meets Garrick, he tells him that he actually read about his adventures as a kid, when they were written by Gardner Fox (how meta can you get?). Garrick says that he had considered retiring, but three of his former enemies, the Fiddler, the Shade, and the Thinker have teamed up. Barry volunteers to help, and the two speed off to the scene of the crime. After they apprehend the villains, Barry returns to his own world.
This story introduced the concept of DC’s “multiverse”. The Golden Age wasn’t an early point in history, it was actually a whole different world. Jay Garrick’s world was revealed to be Earth-One, and Barry Allen’s world as Earth -Two.
This story eventually led to more encounters with Earth-One. Eventually, the Justice Society and the Justice League would team up often. New stories would take place, telling what happened in the years after the comics were no longer published, or being about the old heroes adjusting to a new era.
Also, DC would often have “imaginary stories”, which would explore worlds where key events occurred differently. (Such as Superman killing Batman’s parents, or Batman actually saving them from being murdered.) Others explored probable futures.
The idea of multiple Earths did have its problems, though. Because each Earth had its own history, readers would often be confused about which version they were following, or if the stories on these worlds were even canon. The continuities of these worlds would eventually become more muddled.
I actually thought this story was fun. It was cool to see how the idea of multiple Earths was originally envisioned. I’ll address the changes that occurred when I get to the landmark Crisis On Infinite Earths.