Portraiture, which compelled some attention to Nature, is the latest surviving form of art. In the XXVIth dynasty fairly good heads were occasionally done, but often with some disproportion. The modelled stucco heads of the Roman age are the last stage. Some of them show a real ability and feeling for character (figs. 135 to 137), and one example which can be compared with the skull proves the accuracy of the modelling (fig. 138). The various Schools of Art should now be noticed. The styles of the different periods that we have considered were of course obvious in all the schools; the character of an age affected all parts of the country. Owing to the absence of any artists’ names, and the extreme rarity of those of architects, it is impossible to trace the personal origin of any works. And as we cannot say how much the artists travelled about the country, mere locality does not prove a conclusive test; probably for royal works the artists went to any city according to orders. Among private tombs we can see great differences of style, as between Memphis, Thebes, and Aswan. But the difficulty of exact dating makes comparison doubtful, as we might set side by side works of the rise and of the climax of a period. The most satisfactory evidence about the schools is from the statuary in different materials. When once a sculptor was trained to the peculiarities of one stone he would not be likely to enter on all the difficulties of a fresh material. A man trained for years to slicing and bruising out granite without the least fear of a crack, would not relish hewing soft sandstones that split, or limestone that could not be trusted with its own weight on a finished surface. Certainly the men who learned sculpture on the softer materials would be helpless on the granite. Then we know that the statues were at least dressed into shape--if not entirely finished--at the quarries, and hence the work in one material would continue in the hands of one local school. It is therefore likely that the stone workers of each material formed an unbroken succession, probably in certain families for the most part, and handed on their traditions for several dynasties successively, perhaps even throughout thousands of years. This would not be so much the case in relief sculpture, as there the blocks were built in and sculptured at the building, wherever that might be.