The science of economics lacks an unambiguously strict theory of basic categories, which produces the effect of the inconsistency of the whole theory. This state of affairs is a consequence of the ambiguity of basic terms such as capital, labour, value, money, and consumption. This situation may be positively altered by the inclusion of the fundamental principles of thermodynamics, these include the principle that capital does not arise from nothing and the famous second principle, according to which capital and value are subject to spontaneous, random dispersion. These assumptions made it possible to develop a model of capital and then a theory of human capital measurement. Outlining the framework of a coherent economic theory that incorporates thermodynamic concepts as foundational principles is the main objective of this article. The consistent use of thermodynamics made it possible to reinterpret the system of basic concepts, as well as to solve cognitive problems in the field of capital and labour theory and sources of profit. The strict definition and revelation of the economic fundamentals makes it possible to develop empirical research in the field of human capital and fair wages for labour. The results of the presented empirical research indicate the consistency of the presented theories.