As one piece of evidence for his theory, Hockney points to the extremely realistic way that fabrics look in early Baroque paintings. He argues that without using optical tools, even artistic geniuses would not have been able to paint the elaborate patterns on these fabrics with near-photographic accuracy. Without a camera, how did the artists of antiquity do it? Hockney suggests that they used lenses, prisms, and mirrors to project images of their subject onto a blank wall. Then they could trace the image and, finally, transfer it onto a canvas.