The central doors entering the narthex are two panels high, each of which bore a large cross; these were applied separately, the upper one under a round arch on pilasters, and the lower beneath a gable also supported by pilasters. The lower cross is planted on a rock, from which flow the four rivers, symbol of the Gospel preached to the ends of the earth. Part of a verse in the mosaic of the apse at Nola as given by Paulinus makes this symbolism clear.
“Christ the rock
Of all the church, the base of rock sustains
From which as living streams four fountains flow;
The four evangelists, whose words are gone
Through every land.”
The margins, framing the panel of this pair of doors, are decorated with elliptical hollows and pairs of small rosettes alternately (see [Fig. 66]).
Fig. 66.—Central Bronze Door entering Narthex. Scale about three feet to an inch.
The two doors right and left of this central door are less in size; here each leaf is again divided into two panels. The top one has a relief of a chalice from which rises the stem of a cross with crisp acanthus foliage on either side. The lower panel has a large plain cross. These reliefs are all applied to the panels, the crosses being made up of four arms, which are separately inserted into a central boss. The horizontal arms, and in many instances the whole crosses, have been removed by the Mahommedans. The styles and rails of these doors are inlaid with strap-like forms and gammidae in silver, and engraved with a representation of a setting of gems (see [Fig. 67]). These inlaid straps, with seal-like ends, exactly repeat the forms found on door-hangings. See [Fig. 13]. At S. Sophia the forms have certainly been taken from similar veils. The large simplicity of the design of these beautiful bronze doors suggests that they may be of Justinian’s time.