The affront that many of Caravaggio’s greatest paintings presented to their first audience must have been astonishing: casting a local girl as the Virgin Mary being visited by pilgrims, or the body of a prostitute as her corpse after death; filling almost the entire canvas of Paul’s conversion on the road to Damascus with the horse he’s just fallen from; picturing St. Peter as a terrified and bewildered old man; or putting the dirty feet (or worse) of both pilgrim and executioner right in the viewer’s face.

Yet they all suggest an earthy strangeness that was the reality of piety on the ground, rather than in the books: