Centuries of experimental and theoretical investigations on the speed of light have shown that light does not behave consistently in the various experiments. In some experiments light appeared to behave according to classical ether theory, in other experiments it appeared to behave according to emission theory, and yet in other experiments according to neither theory. In some experiments the speed of light appeared to be constant and in other experiments it appeared to be variable. These confusions have also been expressed in other ways. Is it only the two-way speed or the one-way speed of light also that is constant (or not constant)? Does the speed of light depend on observer’s velocity? Does the speed of light depend on mirror velocity? In this paper, we propose and show that the constancy of the vacuum speed of light, regardless of source/observer/ mirror uniform or non-uniform motions, underlies all the apparent contradictions in the behavior of the speed of light. The fact that some experiments showed non-constancy of the speed of light is only apparent and the speed of light is fundamentally constant c in vacuum for all observers. According to the new theory, Apparent Source Theory (AST ), the speed of light is constant and absolute motion exists at the same time. AST reveals a new distinction that the ether doesn’t exist but absolute motion does exist. Albert Einstein correctly proposed the constancy of the speed of light. However, his interpretation of the light postulate, which is the relativity of space and time, is logically inconsistent and has been disproved experimentally. In this paper, we propose a new interpretation that the constancy of the speed of light points to an intelligent being, God, Who always adjusts the point in space and time where and when light is emitted and the velocity of the center of the wave fronts, so that the speed of light in vacuum is always constant c relative to all observers. In this paper, we show that absolute motion and constancy of the speed of light can co-exist.