Image via WikipediaHow Caravaggio saw in the dark - Telegraph: "The reason for all this is evident. He wasn’t using a conventional method to put a painting together. The standard procedure was to evolve an idealised composition through a series of drawings. Caravaggio didn’t draw at all – or not a single drawing by him survives. Instead, he seems to have worked directly on the canvas, transcribing from reality, with blemishes, imperfections and dirty feet, a detail that infuriated his critics, included. “He claimed,” Bellori wrote, “that he imitated his models so closely that he never made a single brushstroke that he called his own, but said rather that it was nature’s.”"