The carpet page features a cross composed of five squares, arranged in a cross. Each square has a smaller square at its center and has four equal sized squares projecting from each side. The four projections of the central square are shared with the four outer squares, connecting them to the central squares. The entire cross construction projects upwards from a stepped base which occupies the lower third of the design. The background is divided into compartments, each of which is filled with self-contained knot work.
The carpet page bears a strong resemblance to the initial carpet page in the Book of Durrow (Dublin, Trinity College Library, MS 57), which is also features a cross composed of linked squares. Nordenfalk has commented that, although the Durrow cross lacks a stand and is composed of eight rather than five squares, there is such strong agreement in many of the specific details of the composition that there must have been common archetype.
The common archetype may have also served as a model for the four evangelist symbols in the Echternach Gospels. Although the style between the two manuscripts differs greatly and the Diatessaron has all four symbols on the same page and Echternach gives each symbol its own page, the iconography in the two manuscripts is quite similar. Each of the symbols shares a common attitude. For example in both manuscripts the man symbol is facing the viewer with his hands held at his chest, although in Echternach he holds a book while in the Diatessaron he does not. Likewise in both manuscripts the lion is leaping to the right with its two rear paws on the ground. In both manuscripts all of the symbols are full length and lack wings (except for the Eagle of course.)
Nordenfalk argues that the combination of the sudden appearance of the carpet pages and the iconography of the evangelist symbols indicates that there must have been a copy of the Diatessaron available to the makers of the early Insular manuscripts, and the commonalities between the two manuscripts are striking. They are especially striking in light of the extreme separation in time and place between the two manuscripts.
S. E. ASSEMANI, Bibliothecae Mediceae Laurentianae et Palatinae Codicum Mss. Orientalium Catalogus […], Florentiae, ex Typographio Albiziniano, 1742. pp. 59-61.
G. MESSINA, S. J., Notizia su un Diatessaron persiano tradotto dal siriaco, Rome, 1943
G. MESSINA, Diatessaron Persiano. I. Introduzione II. Testo e traduzione, Rome, 1951.
Carl NORDENFALK, Celtic and Anglo-Saxon Painting, New York, George Braziller, 1977., p. 19-21
A. M. PIEMONTESE, Catalogo dei manoscritti persiani conservati nelle Biblioteche d’Italia, Roma, Ist. Pol. e Zecca dello Stato,1989, 104-108
I. PIZZI, Catalogo dei codici persiani della Biblioteca Medicea Laurenziana, Firenze, Tip. dei successori Le Monnier, 1886 (estr. da Cataloghi dei codici orientali di alcune biblioteche d’Italia pubblicati dal Ministero della Pubblica Istruzione, Firenze, 1878), p. 3
G. ULUHOGIAN, Catalogo dei manoscritti armeni delle biblioteche d’Italia, Roma, Istituto Poligrafico e Zecca dello Stato, 2010 (Indici e cataloghi delle biblioteche italiane, Nuova serie, XX), pp. 118-119