He then became interested in spaceflight after reading Hermann Oberth's book Die Rakete zu den Planetenräumen (The Rocket into Interplanetary Space). Although it was a difficult technical book, Ley worked through the calculations and concluded that outer space would soon become the next great frontier of human exploration. Ley was so convinced by Oberth's book that he sat down at the age of 19 to write a popularization of its contents. He also began corresponding with every known rocket enthusiast in Europe, including Oberth himself.
This Willey Ley was an interesting dude.
https://en.wikipedia.org/wiki/Willy_Ley