In Eastern Christianity art and theology go together. They cannot be separated. Both art and theology express the deepest inner feelings of the heart. Art and theology articulate God's living revelation, but art does it in a visible, plastic way. An icon is a picture of a sacred subject which is painted on a panel of wood. The surface beneath is prepared with a mixture of powdered alabaster and glue beneath which linen is sometimes stretched. Colors are laid on, using the yolk of an egg as medium.
— George A. Maloney, Gold, Frankincense, and Myrrh