It remains to note that the scientific study of ancient Roman art dates from a comparatively recent period. The great artists of the Renaissance, headed by Raphael and Michelangelo, showed no lack of appreciation for such models as the reliefs of Trajan's Column ; and Mantegna's "Triumph of Caesar" vividly suggests how great was the influence exerted by Roman historical sculpture upon their choice and treatment of monumental subjects; but their eyes were already fixed on the Greek ideal, however imper fectly represented by the monuments then available. In the 18th century the supremacy of this standard seemed established beyond challenge, and even the vision of the Magnificenza Romana, evoked by Piranesi, failed to arouse any response in Winckelmann and the apologists of Greece. The Greek antique, till then only dimly divined behind the copies that filled the palaces and galleries of Italy, was soon to be made more vivid by the recovery of the buried treasures of Herculaneum and Pompeii and the systematic excavation of the extant remains of Hellenic art, which began early in the i9th century and still continues, not unnaturally absorbed the attention of the majority of classical archaeologists. Nevertheless, towards the close of the i9th century, when the main lines of Greek artistic development had been traced and interest aroused in its later offshoots, critics were led to examine more closely the products of the Roman period. In 1893, Alois Riegl entered the lists on behalf of Roman Art with his Stilfragen, a series of essays on the history of ornament, in one of which he expressed the opinion that "there was in the antique art of the Roman empire a development along the ascending line and not merely a decadence, as is universally believed." This thesis was taken up two years later by Franz Wickhoff in a preface to the reproduction in facsimile of the illustrated ms. of Genesis in the imperial library at Vienna.
In the year following the English translation (by E. Strong) of Wickhoff's work, Riegl published the first (which, by reason of his untimely death, remained the only) volume of his Late Roman Industrial Art (new ed., 1927) in which he endeavoured to show that the later transformations of Roman art in the 2nd and succeeding centuries after Christ continue to mark a definite advance. The fecundity of the leading ideas put forward by Wickhoff and Riegl remains unimpaired, as Koch points out, in spite of the attacks of Josef Strzygowski, who for 3o years and more has never ceased to dispute the originality of Roman art and to insist that Roman artistic achievement, whether of the imperial or early Christian period, was at all times dependant on the Hellenistic East. By thus shifting the ground of controversy from the Mediterranean to the oriental area, Strzygowski, again to quote Koch, has immeasurably broadened the archaeological horizon; but the net result of the long conflict, so far as our enquiry is concerned, has been to bring out more clearly the essential characteristics of Roman art in the pre-Christian period, and its high significance in the formation of the art of the Chris tian West. The case for Roman art is stated anew by G. McN. Rushforth in the chapter "Roman Art and Architecture," con tributed to the Legacy of Rome (1923) and by Herbert Koch in the admirable monograph, Romische Kunst (1925), already quoted. It will be seen from what has been said above that there is a new and growing interest in the post-Constantinian periods of Roman art, down to Justinian and later. Of this we have the proof, not only in Riegl's book quoted above, but also in Delbrueck's magnificent publication of late Roman monuments— done by care of the German Institute—and in all the newer histories of ancient art—Rodenwaldt's for instance.