I have a confession to make. I really enjoyed this book. It’s been a while since I admitted something of the sort, and I feel ashamed, because, although it’s smartly, smoothly written, my pleasure was partly based on titillation. I smirked — I occasionally snickered — at the madder facts of self-mortification, whereby in the Middle Ages the (frequently female) faithful might flaunt their holiness in acts of rank humility.