The upper mosaic of the diakonikon of the basilica of Moses
The decoration of the mosaic of the long northern chapel of the basilica of Moses follows the functional division of the hall divided in two distinct spaces by two steps.
The upper eastern area is decorated with a quadrangular panel enclosed within a four ended polychrome guilloche on a dark background with an inner wavy motif . Outside this band, on the white border along the perimeter of the chapel, a double line of diamond shaped flowers is added. The line of flowers is broken by a knotted circle at the centre of the western side.
The carpet of the panel is laid out as a composition of polylobed squares flanked to form concave twelve-sided polygons containing a square of flowers and a cross of flowers at the centre. In the spaces between the lobes, geometric motives, fruit, flowers, birds and fish are inserted.
Geometric patterns with two rectangles and a rainbowed lozenge are inserted in the first series of spaces near the step. There follows a series of birds (only two remain) facing tufts of flowers. Of the vegetable series there remains an elongated double basket with two spiral shaped handles full of fruits or flowers and an open flower corolla. The fourth series survived completely and we find four motifs: two fish on the outer extremities facing inwards, knotted circles inside a rhombus and a rosetta motif. Two bunches of grapes and two shields rendered by red tesserae and white circles or semicircles form the following series. In the final series we find four fruits depicted with stalk or leaves to the sides: a pomegranate, a cucumber which can be recognized through its form and the white tesserae spots, an oblong fruit, and that which seems to be a big leaf between two smaller leaves.
In the empty space left by the composition, between the polylobed squares and the border, vegetable and geometric motifs where added: rosettas, half corollae, the open stem of a flower and half a diamond.
The long carpet of the lower area is surrounded by a double loose cup shaped guilloche with curved edges with eyelets and a wave motif. The white border, along the perimeter of the chapel is decorated, towards the wall, with one line of flowers and another of diamonds
On the western wall, a double series of diamonds is interrupted by a medallion. Within the circle of the medallion, two interwoven squares, one set on the side the other diagonally, contain a polychromatic rhombus in the centre. On the east side, in the vicinity of the step, the double line of flowers and diamonds is interrupted by a polychromatic shield made of red tesserae decorated internally by a triple sequence of white tesserae which form: small triangles, lozenges, slanting in a clockwise direction and concentric circles at the centre.
The internal space of the carpet is uniformly spaced by a right angled network formed by polychromatic bands which form adjacent knotted squares containing, alternatively heart shaped leaves and corollae of opened flowers.
For the dating of this singular work, mostly geometric and having no icons, we have the terminus post quem of the lower mosaic of the diakonikon-baptistery (530) and the construction of the basilica which precedes the service chapel to the North. Keeping in mind what has already been said for the dating of the basilica, and the probable long use of the diakonikon-baptistery after that date, the construction of the new chapel at the same height of the basilica has to be not before the mid-VI century. The technical qaulities in the laying of the tesserae and the stylish rendering of the whole makes this work share the same qualities of the mosaic of the basilica rather than that of the southern baptismal fount. (597) .