We now proceed to determine the age of this painting--a matter of the greatest importance to our present purpose. What canons of judgment ought to be followed in such an investigation? First, we should attend to the style of the painting, and the degree of artistic perfection it exhibits in conception and execution; secondly, we should confront the results of this first examination with such information as we may be able to collect from a close study of the history, topography, and inscriptions of each subterranean apartment, such a study being admirably calculated to assist us in fixing the date of the painting. To do all this in any given case, is not the work of a few pages, but of a bulky volume. As far as our painting is concerned, all the tests above mentioned serve to prove its extraordinary antiquity. "Any one can see", says our author (_page_ 15), "that the scene depicted in the cemetery of Priscilla is treated in a manner altogether classical, and is a work of the best period of art. The very costume employed therein suggests a very remote antiquity; that is to say the _pallium_, without any under garment, the right arm bared in the figure of the prophet, and still more the short-sleeved tunic on the Virgin. The beauty of the composition, the grace and dignity of the features, the freedom and skill of the drawing, stamp this fresco as belonging to a period of art so flourishing, that, when first I saw it, I thought I had before me one of the oldest specimens of Christian painting in the Catacombs. I spoke of it to my master, the late celebrated P. Marchi, who proceeded to examine it in company with the illustrious Professor Cav. Minardi, now member of the Commission, of Sacred Archaeology, and both pronounced it to be a wonderful specimen of the very earliest Christian art. The learned and the experts in the study of Greco-Roman monuments who have seen this fresco, have declared it to be not later than the time of the first Antonines, and perhaps even prior to that epoch. It remains therefore to collect such proofs as may fix as closely as possible the age of this remarkable monument, which all admit to belong to the first years of Christianity. To this end I will first compare it with other paintings of more or less certain date, and then confront the results of the comparison with the history, topography, and inscriptions of the crypt". He then compares our fresco first with paintings in the cemetery of Callixtus, which it is admitted belong to the days of Popes Pontianus, Anteros, and Fabian, and finds that it is far superior to them in style and execution, and consequently belonging to an older and more classical school. He next compares them with the ornaments of the square crypt, discovered last year in the cemetery of Pretextatus, and belonging to about the year 162. These ornaments, better than the last mentioned, are still inferior to our fresco. Finally, in the cemetery of