In order to appreciate the importance of this relief, it is only necessary to compare it with the processional treatment of similar subjects upon early Christian sarcophagi, where each figure stands up stiff and separate, nor can the controlling and combining artist's thought be traced in any effort after composition.

Ever since the silver age of Hadrian, when a Bithynian slave by his beauty gave a final impulse to the Genius of Greece, sculpture had been gradually declining until nothing was left but a formal repetition of conventional outlines.

The so-called Romanesque and Byzantine styles were but the dotage of second childhood, fumbling with the methods and materials of an irrecoverable past.

It is true, indeed, that unknown mediaeval carvers had shown an instinct for the beautiful as well as great fertility of grotesque invention.

The facades of Lombard churches are covered with fanciful and sometimes forcibly dramatic groups of animals and men in combat; and contemporaneously with Niccola Pisano, many Gothic sculptors of the North were adorning the facades and porches of cathedrals with statuary unrivalled in one style of loveliness.[60] Yet the founder of a line of progressive artists had not arisen, and, except in Italy, the conditions were still wanting under which alone the plastic arts could attain to independence.