The guide-books of modern Rome describe the series of S. Paul's, restored in mosaic after the fire of 1823, as made up of imaginary likenesses except in the case of later Popes. This statement is not correct. The original medallions were painted on each side of the nave, and on the cross or end wall above the entrances. Those of the end wall disappeared long since, on the occasion of some repairs to this part of the basilica. Those of the left side perished in the fire of 1823; but those of the right side, beginning with S. Peter and ending with Innocent (401-417), were saved. They have since been detached from the wall, transferred first to canvas, then to stone, and are now exhibited in one of the corridors of the monastery.[104] As regards those which perished in the fire, they had already been copied, first in the seventeenth century by order of Cardinal Francesco Barberini, and again in 1751 by Marangoni. The new series in mosaic is therefore not all fanciful and imaginary, but follows the tradition of the likenesses as they were first produced in the fifth century. At that time the study of the pontifical succession was receiving considerable attention in Rome. There were written catalogues inserted in liturgical books, which were read to the congregation on certain days of the year, so that everybody could argue on the subject, and remember the order of succession of the bishops. To impress this more forcibly on the minds of the people, it was written on the walls of the newly erected basilica of S. Paul, and illustrated with portraits. The series must have struck the imagination of visitors and pilgrims. The idea of apostolic inheritance, of uninterrupted hierarchy, of the supremacy of the See of Rome, took a definite shape in the array of these busts of bishops, led by S. Peter, and congregated, as it were, around the grave of S. Paul.
[Illustration: _A_ Portrait head of S. Peter; from a medallion in répoussé discovered by Boldetti in the Catacombs of Domitilla.--_B_ Portrait head of S. Paul; from a medallion preserved in the Museo Sacro Vaticano.--Both are works of the second century.]
The custom found imitators in other churches and in other cities. Speaking of the gallery of Popes in the duomo at Siena, Symonds remarks how the accumulated majesty of their busts, larger than life, with solemn faces, each leaning from his separate niche, brings the whole past history of the Church into the presence of its living members. A bishop walking up the nave of Siena must feel as a Roman felt among the waxen images of ancestors renowned in council or war. "Of course," Symonds concludes, "the portraits are imaginary for the most part, but the artists have contrived to vary their features and expressions with great skill." This statement may be correct in a general way, especially in regard to the Middle Ages, but is subject to important exceptions. There is no doubt, for instance, that the likenesses of SS. Peter and Paul have been carefully preserved in Rome ever since their lifetime, and that they were familiar to every one, even to school-children. These portraits have come down to us by scores. They are painted in the cubiculi of the catacombs, engraved in gold leaf in the so-called _vetri cemeteriali_, cast in bronze, hammered in silver or copper, and designed in mosaic.[105] The type never varies: S. Peter's face is full and strong, with short curly hair and beard, while S. Paul appears more wiry and thin, slightly bald, with a long pointed beard. The antiquity and the genuineness of both types cannot be doubted. After the peace of Constantine, when Sylvester, Mark, Damasus, Siricius, and Symmachus began to fill the city with their churches and memorial buildings, and as the habit of exhibiting in each of them portraits of the founders became general, it is evident that the author of the collection of portraits in S. Paul's, which dates from the fifth century, must have had plenty of authentic originals at his disposal.