The mathematical digressions are a fascinating stroll between mathematics and literature. From the models of the geometry of hell (Dante's Divine Comedy) to Petrarch's systematics of the Canzoniere, the mathematics of the devil's wager (Goethe's Faust), and the game-theoretical patterns of mythology, this popular science introduction to poetic mathematics spans a wide arc. The book is aimed at an audience willing to view literary motifs from a mathematical perspective while also approaching the fascination of mathematics in a poetic manner. The stops on this journey follow a well-tempered mathematical score that manages to extract interesting notes from both literature and mathematics.