in Antiquity, a public register containing the names of the consuls and other magistrates among the pagans; and of bishops, martyrs, and others among the Christians.

The word is formed from the Greek διπτυχον, which is compounded of δεξις, twice, and επιστρατη, I fold or plait; though there were some in three, and others in four or five leaves.

There were secular diptycha in the Greek empire, as well as sacred ones in the Greek Church. The former were the matricula or registers wherein the names of the magistrates were entered; in which sense diptycha is a term in the Greek chancery.

The Sacred Diptycha consisted of a double catalogue, one part of which contained the names of the living, and the other those of the dead, which were to be rehearsed during the office. We meet with something not unlike the sacred diptychas of the Greeks in the canon of the mass according to the Latin usage, where the people are enjoined to pray once for the living and once for the dead. In such diptychas were entered the names of bishops who had governed their flock aright; and also the names of such as had done any signal service to the church, whether they were living or dead; and mention was made of them in the celebration of the liturgy.

Casanbon, in his observations on Athenaeus (lib. vi. cap. 14), supposes the Christians to have borrowed the custom of writing names in a book, and rehearsing them at mass, from the heathens, who entered the names of persons to whom they wished to do any signal honour in the verses of the Salis, as was done in the case of Germanicus and Verus, sons of the emperor Marcus Aurelius, and a long time before, during the ages of the republic; in that of Marcus Vetusius and Lucia Volumnia, as we are told by Tacitus, Spartan, Ovid, Festus, Plutarch, and others. But Rosweyd does not approve of this notion of Casanbon; and the pretended St Dionysius, a very ancient author, asserts that this usage was originally founded on Scripture (2 Tim. ii. 19; Psal. cxvi. 15). Rosweyd adds Ecclesiasticus (xlv. 1), and maintains these to have been the passages which the ancient church had in view, rather than the Salian verses.

The secular diptycha were frequently sent as presents to princes and others, on which occasions they were finely gilded and embellished; as appears from Symmachus (lib. ii. ep. 81). Those presented were usually of ivory. The first law, De Expensis, Ludor. in C. Theod. forbids all magistrates below the rank of consuls to make presents of diptycha of ivory in the public ceremonies.