Diptyches were used among the Romans for all kinds of purposes, such as to convey love-messages, as invitations to a banquet, or to notify the celebration of feasts and games. We find the diptych also used in Christian temples from the time of Constantine, serving to record church festivals or names of saints and martyrs, as covers for a copy of the gospel (_diptycha evangeliorum_), or as reliquaries (_thecae reliquiarum_). Sometimes these diptyches were wrought expressly for the church, or sometimes they were consular diptyches that had been preserved from former ages. This latter class, when cleansed from pagan usage and devoted to the ceremonies of the Christian faith, was known as _diptycha mixta_. Such early objects as were wrought in ivory by Spanish hands, consisting as a rule of circular or oblong, square or oval caskets, were principally carved by Moors or Mudejares. Among the Spanish-Moorish boxes which are still preserved are several of the greatest interest and beauty (Plates xxxviii., xxxix., xl.). One of them, made from pieces of an older casket believed to date from earlier than the Moorish conquest, is in the National Museum. The decoration in its present form consists of Arabic inscriptions in relief, together with figures of the apostles. This casket, which proceeds from the Colegiata of Saint Isidore at León, measures seven inches in length by five in depth and six in height, and has been used as a reliquary. Another, dating from the middle of the eleventh century and proceeding from the same temple as the one just noticed, is also in the National Museum. It was a present from the Emir Mohammed Almotamid-Aben-Abed to his second wife, Al-Badir ("the Moon"), and includes among the decoration dogs and doves, symbolic of affection and fidelity. The style of carving is what is known as Persian-Arabic. We do not know, however, whether the box was imported from the East, or whether it was made in Spain by somebody of Persian parentage or skilled in Persian art. The material is a delicate _taracea_ of sandal, aloe, and cypress woods inlaid on larch. The box, which was used at León as a reliquary, has bronze clasps, and is inscribed along the top with sentences from which we learn that it was made by Aben-As-Serag. [Illustration: XXXVIII IVORY CASKET (_Moorish; 11th Century. Pamplona Cathedral_)]