1911 Encyclopædia Britannica/Diptych
DIPTYCH (Gr. διπτυχος, two-folding), (1) A tablet made with a hinge to open and shut, used in the Roman empire for letters (especially love-letters), and official tokens of the commencement of a consul’s, praetor’s or aedile’s term of office. The latter variety of diptych was inscribed with the magistrate’s name and bore his portrait, and was issued to his friends and the public generally. They were made of boxwood or maple. More costly examples were in cedar, ivory (q.v.), silver or sometimes gold. They were often sent as New Year gifts.
(2) In the primitive church when the worshippers brought their own offerings of bread and wine, from which were taken the Communion elements, the names of the contributors were recorded on diptychs and read aloud. To these names were early added those of deceased members of the community whom it was desired to commemorate. This custom rapidly developed into a kind of commemoration of saints and benefactors, living and dead; especially, in each church, were the names of those who had been its bishops recorded. The custom was maintained until the lists became so long that it was impossible to read them through, and the observance in this form had to be abandoned. The insertion of a name on the diptych, thereby securing the prayers of the church, was a privilege from which a person could be excluded on account of suspicion of heresy or by the intrigues of enemies. His name could, if written, be expunged under similar circumstances. The names thus written were read from the ambo, in which the diptych was kept. The reading of these names during the canon of the mass gave rise to the term canonization. By various councils it was ordained that the name of the pope should always be inserted in the diptych list.
The addition of dates resulted from the custom of recording baptisms and deaths; and thus the diptych developed into a calendar and formed the germ of the elaborate system of festologies, martyrologies and calendars which developed in the church.
The diptych went by various names in the early church—mystical tablets, anniversary books, ecclesiastical matriculation registers or books of the living. According to the names inscribed, bishops, the dead or the living, a diptych might be a diptycha episcoporum, diptycha mortuorum or diptycha vivorum.
In course of time the list of the names swelled to such proportions that the space afforded by the diptych was insufficient. A third fold was consequently provided, and the tablet became a triptych (though the name diptych was retained as a general term for the object). Further room was afforded by the insertion of leaves of parchment or wood between the folds. The custom of reading names from the diptychs died out about the 8th century. The diptychs, however, were retained as altar ornaments. From the original consular documents onwards, the outsides of the folds had always been richly ornamented, and when they ceased to be of immediate practical use they became merely decorative. Instead of the list of names the inside was ornamented like the outer, and in the middle ages the best painters of the day would often paint them. When folded, the portraits of the donor and his wife might be shown; when open there would be three paintings, one on each fold, of a religious character.