Observe, first, the shape of the space that Raphael was called upon to decorate. It is known as a lunette or moon-shape. Now it was this space and no other, that for the time being, he had to decorate. What he put into it, must be suggested by, one may almost say, must grow out of, the particular shape of this space. In fact, the outside lines of the lunette, and the lines inside, must _together_ form the pattern of the composition. Now observe how he did it. Briefly, he put into it a number of curved lines, that would repeat the curve of the outside, and sometimes also be in contrast to it. Likewise he introduced horizontal lines, to repeat the bottom edge, and vertical ones in contrast. Let us examine it more closely.