Diptych triptych form, with two outer panels that could be closed across the main central representation. They are one type of the multi-panel forms of painting known as "polyptychs". The diptych was a common format in Early Netherlandish painting and depicted subjects ranging from secular portraiture to religious personages and stories. Often a portrait and a Madonna and Child had a leaf each. It was especially popular in the 15th and 16th centuries. Painters such as Jan van Eyck, Rogier van der Weyden, Hans Memling and Hugo van der Goes used the form. Some modern artists have used the term in
San Marco Altarpiece of cast shadows towards the bottom edges of the draperies in the painting, which are indicative of how Angelico gave the medieval equation of earthly and heavenly beauty new immediacy by translating it into the rational language of a representational style. In addition, as Angelico implies in other ways, glazing was a technique used to create yet another boundary between the real world and the pictorial illusion. San Marco Altarpiece The San Marco Altarpiece (also known as "Madonna and Saints") is a painting by the Italian early Renaissance painter Fra Angelico, housed in the San Marco Museum of Florence, Italy.