One of the more speculative tales surrounding the Shroud of Turin, which supposedly depicts the face of Jesus Christ, purports that the cloth was actually made by Leonardo da Vinci. The story goes that Leonardo passed off his own image as Christ’s, possibly as an act of hubris or to trick the Catholic Church. The theory has merits. According to traditional belief, Jesus imparted his image to his burial cloth when he was wrapped in it, but radiocarbon testing has dated the fabric to the Middle Ages. Yet dating the image’s genesis even to the 14th century is mystifying. The linen fiber is neither painted nor dyed—how was the image made?