…A particularly impressive achievement of the artist is found in the sensitively rendered heads of the figures. The intention seems to have been to racially distinguish the twins. The facial traits of the figure on the right exhibit pronounced black features, while the aquiline nose of his companion is normative for a person of European origin.
A clue to the meaning of the relief lies in the activity performed by the figures. Their raised arms support the lower edge of a short horizontal block, while the angled form on which their advancing legs are placed resembles a column base. Between these two conventional structures, the twins themselves serve as atlantes—that is, supporting elements in the form of human figures who bear the now missing frame of the relief.
The inherent notion of support so originally achieved here may also allude to the celestial context of the sign, which “holds” the sun during the spring on its transit through the zodiac. Born of the same mother, the twins of different races reflect dual natures of the same entity, working harmoniously together. The medieval tendency to project a resolution of opposites seems here to evoke the universe held in a state of dynamic balance…
