Consular diptych

In Late Antiquity, a consular diptych was a type of diptych intended as a de-luxe commemorative object. The diptychs were generally in ivory, wood or metal and decorated with rich relief sculpture. A consular diptych was commissioned by a consul ordinarius to mark his entry to that post, and was distributed as a commemorative reward to those who had supported his candidature or might support him in future.

From as early as the first century CE, some formal letters of appointment to office were known as "codicilli", little books, two or more flat pieces of (usually) wood, joined by clasps, lined with wax on which was written the letter of appointment. Later, the letter might be written on papyrus and presented within the covers. By the late fourth century, however, specially-commissioned diptychs began to be included among the gifts that appointees to high office distributed to celebrate and publicize the public games that were their principal duties. These diptychs were made of ivory, with relief carvings on the outside chosen by the donor, looking superficially similar to codicils but containing no writing and with no official status.

The routine distribution of such diptychs in the East is marked by a decision by Theodosius I in 384 to limit expenditure on the games of Constantinople by reserving ivory diptychs (and golden gifts) to consuls alone. In the western empire, they became a usual part of the public displays given by great aristocrats. Quintus Aurelius Symmachus, for example, distributed some to commemorate his son's quaestorian games in 393 and praetorian games in 401 respectively. Almost all depict the games, and on three separate occasions Symmachus links the presentation of these diptychs with the completion of the games. Their end is marked by the consulship's disappearance under the reign of Justinian in 541.

The oldest diptych that can properly be called a consular diptych, held in the cathedral treasury at Aosta, is one commissioned by Anicius Petronius Probus, consul in the Western Empire in 406 – it is unique not only for its extreme antiquity but also as the only one to bear the portrait of the Emperor (Honorius in this instance, to whom the diptych is dedicated in an inscription full of humility, with Probus calling himself the emperor's "" or slave) rather than that of the consul.

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