One of the most important Christian Humanists of the 20th century, Francois Mauriac is largely now forgotten. Here’s the book Mauriac wrote for Christopher Dawson’s edited series, ESSAYS IN ORDER. It would be, technically, vol. 15, though it’s listed as “New Series: No. I” Sheed and Ward published a total of 16 ESSAYS. Each is meant to be read in a single sitting.
It’s also worth remembering that Mauriac was awarded the Nobel Prize in Literature in 1952, back when it meant quite a bit to win such a thing.