Facing due west, and concealed by the Churrigueresque façade, is the most wonderfully sculptured portico that human eye has yet seen. This portico, or _narthex_,[143] was originally part of the exterior; now it is part of the interior of the cathedral. It was once an open façade; the pillars which supported its front on either side stood far apart, and pilgrims caught sight of its beauty even before they entered the building, and rain and wind as well as daylight and sunlight played freely upon the flesh-coloured and lifelike features of the sculptured saints. But in our day the brickwork of the modern façade so darkens the portico that even when the doors are flung open it is never seen at its best. A triple archway gives entrance to the three naves of the cathedral; the central arch fronts the principal nave, and the smaller arches (to the north and south), the two collateral naves, or, as some would call them, the side aisles. These three arches and their tympana are covered with statues which have been adapted to the architecture with such skill that at a little distance they appear to be carved out of the actual material of which the arches are composed. Examined closely, every statue, every ornament is a masterpiece of delicate sculpture. The whole is intended to represent the Christian Church--the entrance to the House of God, of which Christ is “the chief Corner-Stone.”[144] It is to the walls of the catacombs that we must turn for the origin of Western Christian art. In the West, as Didron has pointed out, the Christian painters limited themselves to a small cycle of subjects. Setting history and chronology aside, they treated their subjects solely with reference to some hidden moral or devotional truth which they were known to signify. Thus the events recorded were represented by symbols. A system of such symbols was developed which illustrated the most salient points in the Christian faith. A hieratic cycle of subjects came into use, not necessarily for doctrinal purposes, but as expressive of religious facts.[145] In the days when few, even among the rich, could read, outside the monasteries, pictures and statues were the most potent medium by which the contents of the Bible could be explained to the general public. Even in our day pictures represent words to the illiterate Russian peasant; when he goes to the neighbouring town to purchase an agricultural implement or a new coat, he enters such shops as have similar articles painted in brilliant colours above their respective doors. Gregory of Tours, writing towards the close of the sixth century, tells a pretty story of how Namatea, the aged widow of Namatius, bishop of Auvergne (A.D. 423), reads to the painter decorating the walls of the church she has raised over her husband’s tomb the scenes he is to depict with his brush: “She used to sit with a book upon her knees reading thereout stories of the deeds of the men of old.”[146]