A diptych is a painting, relief carving, or any other work of art made of two equal sized parts. In the Renaissance period, the two parts of a diptych faced one another like the pages of a book and were hinged together to protect the interior painting as well as to ensure that the work could be folded and easily transported when not on display. Diptychs were invariably small in size and, in the case of altarpieces, they were used for private devotion. While initially used for writing tablets, the outer surfaces being carved with wax on the hollowed inner surfaces, diptychs were also used to commemorate family events such as weddings, and to mark the appointment of a new consul.