166

Classification of the Sci.
30

who is acquainted with the fundamentals of dynamics that if physical forces obey the law of the conservation of energy then a volition cannot be a force. For a volition tends to bring about a result and if circumstances are varied the action will be varied, so far as may seem necessary to bring about that result; while a force acting according to the law of energy; simply a conservative force does not act in this way. It produces or rather is an instantaneous acceleration (which its law, if anything, determines as synchronous with a configuration) and this acceleration integrates itself by the intervention of time, into motion and on