The paintings of the catacombs date from the third and fourth centuries after Christ. The catacombs, or burial-places of the early Christians, consist of long, narrow, subterranean passages, cut with regularity, and crossing each other like streets in a city. The graves are in the sides of these passages, and there are some larger rooms or chambers into which the narrow passages run. There are about sixty of the catacombs in and near Rome; they are generally called by the name of some saint who is buried in them. The paintings are in the chambers, of which there are sometimes several quite near each other. The reason for their being in these underground places was that Christians were so persecuted under the Romans, that they were obliged to do secretly all that they did as Christians, so that no attention should be attracted to them. The principal characteristics of these pictures are a simple majesty and earnestness of effect; perhaps spirituality is the word to use, for by these paintings the early Christians desired to express their belief in the religion of Christ, and especially in the immortality of the soul, which was a very precious doctrine to them. The catacombs of Rome were more numerous and important than those of any other city. Many of the paintings in the catacombs had a symbolic meaning, beyond the plainer intention which appeared at the first sight of them: you will know what I mean when I say that not only was this picture of Moses striking the rock intended to represent an historical fact in the life of Moses, but the flowing water was also regarded as a type of the blessing of Christian baptism. [Illustration: FIG. 17.--MOSES. _From a painting in the Catacomb of S. Agnes._] [Illustration: FIG. 18.--DECORATION OF A ROOF. _Catacomb of S. Domitilla._] The walls of the chambers of the catacombs are laid out in such a manner as to have the effect of decorated apartments, just as was done in the pagan tombs, and sometimes the pictures were a strange union of pagan and Christian devices. The above cut, from the Catacomb of S. Domitilla, has in the centre the pagan god Orpheus playing his lyre, while in the alternate compartments of the border are the following Christian subjects: 1, David with the Sling; 2, Moses Striking the Rock; 3, Daniel in the Lion's Den; 4, The Raising of Lazarus. The other small divisions have pictures of sacrificial animals. These two cuts will give you an idea of the catacomb wall-paintings.