The Michelson-Morley experiment was flawed in that it was meant to detect something that never existed: the ether. The ether hypothesis should have been subjected to a thorough conceptual test even before doing a physical experiment. The Michelson-Morley experiment was capable to detect the ether, but was/is incapable to detect absolute motion. The terms ‘absolute motion’ and ‘motion relative to ether’ were always wrongly presumed to be the same. Despite the failure of Michelson-Morley experiment, absolute motion was detected with several other kinds of experiments, such as the Sagnac, the Michelson-Gale, the Marinov, the Silvertooth, the Roland De Witte experiments. A new interpretation of absolute motion and the speed of light is proposed in this paper: the speed of light is constant relative to the apparent source. The effect of absolute motion is to create an apparent change in the position (distance and direction) of a light source relative to the observer, for absolutely co-moving source and observer. For absolutely co-moving source and observer, the effect of absolute motion is to create a change in the path length, and not the speed, of light. Apparent Source Theory ( AST) consistently explains the Michelson- Morley experiment, Sagnac effect and moving source experiments. Any true theory of the speed of light should convincingly explain both the Michelson-Morley and Sagnac experiments before making any other claims. AST hints on the fundamental nature of light itself. Light is a dual phenomenon : local and non-local.