I'm now doing research and studying the conservation of energy problems. Recently I came across interesting information that the discovery of the law of conservation of energy had an impact not only on the development of physical sciences, but also on the philosophy of the XIX century. With the name of Robert Mayer (the German physician, who first realized and formulated the universality of the law of conservation of energy) is associated with the emergence of the so-called natural-science energy - a worldview that reduces everything existing and occurring to energy, its movement and interconversion. In particular, matter and spirit in this view are forms of manifestation of energy. The main representative of this direction of energy is the German chemist Wilhelm Ostwald, whose highest imperative philosophy was the slogan "Do not waste any energy, use it!"