The Tetramorph featured here complements the preceding illustration. The four living beings portrayed in addition to the twenty-four Ancients had already appeared in the heavenly court in the Old Testament, and in Ezekiel, Isaiah and Daniel. In the explanatio, the living beings and the ancients constitute the symbolic personification of the Law. These four animals represent the four evangelists and the Gospels, a point which, as Beatus himself acknowledges, concords with St Augustine. The identification of the lion with St Mark, the bull with St Luke, and the eagle with St John was adopted by St Jerome, becoming traditional from that moment onwards.
Given the absence of the illustration in Valcavado and taking into account the parallels to be found between the image in the Silos Beatus and the one in Ferdinand I (f. 116v), it is possible to suggest a common source derived from the simpler Morgan Beatus (f. 87), which does not feature Christ enthroned. This is the origin of the circular structure evoking a dome. It has been interpreted as a cosmic vision formed by two concentric circles whose static meaning is seen by M. Schapiro to contrast sharply with the movement of the figures in Hell. The central figure in the group is the Lamb (Agnus D[e]i), the focal point set inside the central circle.
Positioned around the Lamb, within the space between this ring and the outside, are the four evangelists with the heads of the respective symbolic animals upon the wheels of Ezekiel. This clear identification has obviated the respective texts. The Ancients have been reduced to twelve, four of whom are prostrated in front of the evangelists. The others are not seated but standing in pairs, some playing musical instruments whilst others hold the lamps.
Using Maius as a basis, the miniaturist has placed particular emphasis on identifying the functions of the Ancients. Maius incorporated the representation of the musician Ancients into the iconographic repertory of the Beatus belonging to stemma II – a convention upheld in the Silos Beatus.
In this codex, one can perceive the deliberate differentiation between symbolic concepts and those concerning the earthly world, in terms of both the garb of the musicians and the musical instruments. In this illustration they wear ankle-length garments beneath long cloaks like sacred figures, whilst the chosen ones on f. 164 are in contemporary dress with short tunics. Some are prostrated before the Lamb whilst others hold gold phials of perfume (fialas), the saints’ prayers, and musical instruments (citaras) which are identified around the inner circle, replacing Maius’ legend quatuor animalia by isti tenentes citaras. The word zither has been expressed by actual musical instruments, which is quite uncommon in comparison with other earlier and contemporary manuscripts belonging to European stemmata. Alongside the figures are legends that read: auorsas; isti plenum incensum. These legends lack the clarity of those in Maius. The word tronum, in reference to the Lamb’s throne, which appears twice outside the circle in Maius, has been eliminated here. No one is worthy enough to open the book, causing John to weep. One of the Ancients informs him that the seven seals will be broken by the Lamb.
The top band shows Christ enthroned outside the circles holding the Book of the Revelation written inside and out, and sealed with the seven seals. He is set inside a mandorla surrounded by stars and held by a cherubin and a serafin.