In book-publishing you can run all the P&Ls, focus-groups, forced-publicity, social-media-presence you want and still only HOPE for a hit. And sometimes you just get lucky.
If you are a Jesuit publishing house right now, you are in luck: the first (and only) Jesuit pope (you can bet it won't happen again in our lifetime) who is media-savvy, down-to-earth, and, most importantly, a writer, is also a media sensation. Rare is the week that Papa Francesco isn't in the news. Right now his highly-anticipated Encyclical Letter on the environment, On Care For Our Common Home