The unusual optical properties of the moon are summarized. They imply that the fine-grained, compressible material observed by the Surveyor television cameras is representative of the entire lunar surface and very probably of the surfaces of Mercury, Mars, and the asteroids also. The soil is the result of repeated meteorite impacts and is not an ash flow. Evidence for darkening is examined, and it is concluded that a process is acting on the lunar surface to alter the albedo and color of the rock powder. Materials of chondritic or granitic composition are not prevalent on the moon. Differences in the optical properties of the maria and the highlands imply that the soil cover is thicker in the highlands than in the maria and that the high-land soils are laterally more homogeneous than are those of the maria.