ABSTRACT
The most direct and in a sense the most important problem that our conscious knowledge of nature should enable us to solve is the anticipation of future events. Kinematics, or the science of pure motion, confines itself to connecting the two ideas of space and time. Galileo’s conception of inertia supplies a connection only between space, time, and mass. Weighty evidence seems to be furnished by the statements, which one hears with wearisome frequency, that the nature of force is still a mystery, that one of the chief problems of physics is the investigation of the nature of force, and so on. And the balance of evidence will be entirely in favor of the third picture when a second approximation to the truth can be attained by tracing back the supposed actions-at-a-distance to motions in an all-pervading medium. This is the field in which the decisive battle between these different fundamental assumptions of mechanics must be fought out.
