Luther's Groaning Bones

In the winter of 1515, Martin Luther knelt in his cramped cell at the Black Cloister in Wittenberg, his body gaunt from fasting and sleepless nights. For years, the young Augustinian monk had confessed his sins for hours at a stretch — sometimes six hours in a single session — cataloging every wayward thought, every impure motive, every failure to love God perfectly.…