The explicit words "Mach Principle" seem to have been first used by Einstein in connection with the field equations of general relativity, in accordance with which the inertia of local masses is determined by the distribution of mass throughout the entire universe. Mach enunciated the ideas which are at the basis of his "principle" in the course of a critique of Newton's treatment of his laws of motion. Mach strenuously objected to Newton's recognition of two kinds of space and time, relative and absolute. Mach's mathematical analysis took a form which led to his attitude and conclusions very naturally. From the very beginning he used Newton's law of motion in the conventional form: force equals mass times acceleration. The actual stellar universe functions as such a system to the extent that the stellar objects are force-free. "Force-free" means that they exert no detectable forces on local objects and exert no mutual forces on each other.