The Egyptians often referred to the sun and the moon as the "eyes” of particular gods. The right eye of the god Horus, for instance, was equated with the sun, and his left eye equated with the moon. At times the Egyptians called the lunar eye the "Eye of Horus", a concept with its own complex mythology and symbolism, and called the solar eye the "Eye of Ra"—Ra being the preeminent sun god in ancient Egyptian religion. However, in Egyptian belief, many terms and concepts are fluid, so the sun could also be called the "Eye of Horus".