As with poetry, so with the arts of sculpture and painting: the greatest works result from simple designs. All the sculptures which we recognize as sublime or highly beautiful, consist of single figures, or in very rare cases, groups of two or three, and indeed it is difficult to hold in our minds a carved group of several figures. The images of the Zeus and Athena of Phidias, though we know little of them except from literary records and inferior copies, are far more brilliantly mirrored upon our minds than the Parthenon reliefs. The importance of simplicity is perhaps more readily seen in sculpture than in any other art, for the slightest fault in design has an immediate effect upon the mind of the observer. It is noticeable that the decadence of a great art period is usually first marked by complications in sculptured figures.[25] In painting, the pictures which we regard as great are characterized by their simplicity, and the immediate recognition of their purport. They are either ideal figures, or groups where at least the central figure is idealized and commonly known. The work must be grasped at one glance for the beauty to be of a high order. Hence in the case of frescoes great artists have not attempted to make the beauty of any part dependent upon the comprehension of the whole. It is impossible for the eye to take in at a single glance the whole of a large fresco painting, and this explains why a fresco celebrated for its beauty is often disappointing to one who sees it for the first time, and endeavours to impress it on his mind as a single picture by rapidly piecing together the different parts.[26] Polygnotus could well paint forty scenes from Homer as mural decoration in one hall, for they could only be examined and understood as separate pictures; and the ceiling of Michelangelo at the Vatican is so arranged that there is no necessity for combining the parts in the mind. So with the Parma frescoes of Correggio. Raphael had a different task in his Vatican frescoes, but he accomplished it by arranging his figures so that each separate group is a beautiful picture; and Lionardo in his great work at Milan divided the Apostles into groups of three in order to minimize the consideration necessary for the appreciation of so large a work.