It is quite a hard nut and bitter pill for our metaphysician that motion should find its measure in its opposite rest. It is such a glaring contradiction, and every contradiction is an absurdity in the eyes of Herr Duehring. It is nevertheless true that the hanging stone by reason of its weight and its distance from the ground represents a means of mechanical movement sufficiently easily measured in different ways, as for example through gravity direct, through glancing on an incline or through the undulation of a wave--and it is just the same with a loaded gun. The expression of motion in terms of its opposite rest presents no difficulty at all to the dialectic philosophy. The whole contradiction in its eyes is merely relative, for absolute rest, complete equipose does not exist. The movement of the particles strives towards equipose, the movement of the mass in turn destroys the equipose, so that rest and equipose where they occur are the results of arrested motion, and it is evident that this motion is capable of being measured in respect of its results, of being expressed in itself and of being restored in some form or other external to itself. But Herr Duehring would never be satisfied with such a simple explanation of the matter. Like a good metaphysician he creates a yawning gulf between motion and equipose which does not really exist and then wonders if he can find no bridge across the self-created chasm. He might just as well bestride his metaphysical Rosinante and hunt the "Ding an Sich" of Kant since it is in the last analysis nothing else than this which stands behind the undiscoverable bridge. But what about the mechanical theory of heat and of latent heat which is a "stumbling block" in the path of the theory?