Contour and contrast.

"WHEN a dog bites a man, that is not news . . . But if a man bites a dog, that is news," so wrote John B. Bogart, City Editor of The Sun in New York many years ago. The relation between contour and contrast is similar. It is not news, but old and common knowledge that it is the contrast, or difference, in the brightness or color of two adjacent areas that causes the appearance of a contour between them. And so dominant are contours in our visual perception that it seems almost instinctive for us to draw first the outlines of any object that we attempt to portray. Instinctive or not, the practice is at least as old as the most ancient evidence of how man interprets what he sees -"line drawings" are found in some of the oldest