Clausius emphasizes that its thermodynamic studies have not been associated with any idea of ??the thermal motion. All made in the first part of "The mechanical theory of heat" conclusions "are based on the laws of some grievances which can be regarded as correct, without making any specific assumptions about the nature of heat." This commonality thermodynamic methods, for the first time clearly stated by Clausius, thermodynamics makes an extremely powerful research tool, applicable in all areas of physical science. However Clausius admits that his study "were not free from the idea of ??a hypothesis" and that he "at the beginning of their work related to the heat ... tried to understand the internal state of a heated body movement and made it a Statement performance...".