The May Book of the Month is Journey Through Genius: The great theorems of mathematics by William Dunham, first published by John Wiley in 1990, and republished in Penguin Paperback in 1991.
Dunham places each theorem within its historical context and explores the life of the creator — from Archimedes to Gerolamo Cardano to Georg Cantor. He also provides step-by-step proofs for the theorems, each easily accessible to readers with no more than a knowledge of high school mathematics. His approach is to present this material as a work of art like music or literature.