The drool-worthy home-library (complete with a Neitchzean chaise and sliding-ladder!) in Joshua Henkin’s home is its best feature—and he knows it. But that’s not to say the rest of this Park Slope brownstone is anything less than idyllic. If you guessed that such a bibliophile would be a writer, you’d be right. Like Henkin’s earlier books, Matrimony and Swimming Across the Hudson, his latest novel, The World Without You, has been making quite the splash.