Mary Delany was seventy-two years old when she noticed a petal drop from a geranium. In a flash of inspiration, she picked up her scissors and cut out a paper replica of the petal, inventing the art of collage. It was the summer of 1772, in England. During the next ten years she completed nearly a thousand cut-paper botanicals (which she called mosaicks) so accurate that botanists still refer to them. Poet-biographer Molly Peacock uses close-ups of...