Altarpiece unclear. Altarpieces can still broadly be divided into two types, the "reredos", which signifies a large and often complex wooden or stone altarpiece, and the "retable", an altarpiece with panels either painted or with reliefs. Retables are placed directly on the altar or on a surface behind it; a reredos typically rises from the floor. Retable-type altarpieces are often made up of two or more separate panels created using a technique known as panel painting. The panels can also display reliefs or sculpture in the round, either polychrome or un-painted. It is then called a diptych, triptych or polyptych for
Early Netherlandish painting reflection and prayer was encouraged and the small-scale diptych fitted this purpose. It became popular among the newly emerging middle class and the more affluent monasteries across the Low Countries and northern Germany. Ainsworth says that regardless of size, whether a large altarpiece or a small diptych, Netherlandish painting is a "matter of small scale and meticulous detail". The small size was meant to entice the viewer into a meditative state for personal devotion and perhaps the "experience of miraculous visions". Late 20th-century technical examination has shown significant differences in technique and style between the panels of individual diptychs. The