The views expressed by Wickhoff upon Roman Art have been widely accepted, as far as concerns monuments whose Roman origin was undoubted. Riegl has approved the ‘shadow theory’ and explained it in his own peculiar art dialect. Petersen alone has combated it; and with such effect as practically to destroy all belief in this theory, which is Wickhoff's main principle in the appreciation of Roman reliefs, especially those of the Flavian period. Since the relief fragments to be discussed in this paper are attributed to the Flavian period, it is necessary to state Wickhoff's views, and their refutation.
Wickhoff remarks that the artist of the Ara Pacis who, he considers, broke with Greek tradition and made a new departure in relief style, ‘allowed the figures in high relief of the front row [of the procession] to cast their shadows on a back row of figures, which were worked so flat on the ground that they could no longer cast any shadows, but stood like silhouettes against the sky.’ …‘When the shadows of the front row of figures fell on them and they themselves cast no shadow, the illusion was created that their shadow fell on the earth behind them, and thus the background vanished behind them.’