 What made Pocket Book #1 of revolutionary importance was that it was the first "mass-market" paperback; mass market paperbacks allowed people of modest means not only to own books they otherwise could not afford, but also to slip the paperback into their pocket for casual reading on the go, hence the name "Pocket Book".By the 1960s, Pocket Books alone, over the course of more than 40 printings, had sold several million copies of "Lost Horizon", helping to make it one of the most popular novels of the 20th Century.United States President Franklin D. Roosevelt named the Presidential hideaway in Maryland after Shangri-La.