Diptych

A diptych (/ˈdɪptɪk/; from the Greek δίπτυχον,di "two" + ptychē "fold") is any object with two flat plates attached at a hinge. In particular the standard notebook and school exercise book of the ancient world was the diptych consisting of a pair of such plates that were wax tablets, with on their inside faces a recessed space filled with wax. This took writing made with a pointed stylus. When the notes were no longer needed the wax could be slightly heated and then smoothed to allow reuse. Ordinary versions had wooden frames, but luxury ones were made in more expensive materials.

Art

In Late Antiquity, ivory notebook diptychs with covers carved in low relief on the outer faces were a significant art-form: the "consular diptych" was made to celebrate an individual's becoming Roman consul, when they seem to have been made in sets and distributed by the new consul to friends and followers. Others may have been made to celebrate a wedding, or, perhaps like the Poet and Muse diptych at Monza, simply commissioned for private use. Some of the most important surviving works of the Late Roman Empire are diptychs, of which some dozens survive, preserved in some instances by being reversed and re-used as book covers. The largest surviving Byzantine ivory panel (428 mm × 143 mm), is a leaf from a diptych in the Justinian court manner of c. 525–50, which features an archangel.