quickly from her head to her foot, to her right hand, to her head again, etc. Now you realize that the white mass is contained in a distinct triangle. That triangle is the pattern of the picture. Whether you like it or not makes no difference; the triangular path must be followed by your eyes.
This little exercise shows that the eyes, unlike the lens of a camera, cannot see every part of a picture at once, but must range over it from point to point, repeating the tour again and again as long as the picture is in view. But, if we cannot see head, hand, and foot at once, it is evident that we must remember the head while we are observing the hand, that we must remember both the head and the hand while we are observing the foot, etc., else the whole picture could never be built up in our minds. It is also evident that the smoother the path, the more easily and quickly can the tour of inspection be made.
The eye needs paths, finger-posts, and bridges to carry it from one part of a picture to another, a need which painters discovered ages ago, and responded to by uniting the lines of their drawings into some sort of image or design. Thus the old masters often constructed their paintings on the design of a circle, a rectangle, a triangle, a diamond, a right-angled cross, an X shape, an S curve, or some other equally simple pattern, finding by experience that this practice always helped the beholder to grasp the picture as a unity. But they were real magicians, those medieval masters, and as such knew how to conceal their designs. Their technique, which the probing critic lays bare, is neither seen nor suspected by the average beholder who stands worshipful before their paintings. In fact, the tech-
