The foundation of energetics currently consists, alongside the principle of conservation of energy, of the statement established by Clausius, which asserts that heat cannot spontaneously transfer from a colder body to a warmer one. According to its author, this is a principle of equal importance to the idea that one cannot create work from nothing. Indeed, when one considers the current state of science, one must agree with Clausius on this point; one could almost say that his principle is of greater importance than even the principle of energy conservation, as it aims to determine the direction of natural processes, while the latter seems only to establish their quantitative relationships. However, the ideal significance of both statements is by no means reflected in their subordinate arrangement. For the statement by Clausius is far from being as general as the principle.