This painting is simply a study of a technique taught to me as the "Van Eyck technique," oil glazes over a tempera base. Tempera is a very ancient method of painting (colored pigment mixed with a water-soluble medium, often egg yolk). Some of the earliest examples are found on Egyptian sarcophagi. The technique of using oil as the medium, rather than a water-soluble one, was invented much later and may have originated in Afghanistan, migrating to the West during the Middle Ages. The earliest oil painting in the west seems to have been a done in this combined technique. It's found in early Netherlandish painting such as the Van Eyck brother's.