This scientific work researches the private law principles proceeding from essence of private law and its ratio with the public law. The analysis of scientific thought classics analysis in the specified sphere allows to reflect a scientific view point of authors in the matter as the category "legal principle" takes the important place in law system, and the importance of the private-law relations for the state activity in economic area determines a research as necessary for studying, both by lawyers-theorists, and experts lawyers. The considered problem reflecting essence of private law through a prism of its legal principles shall be the base for the solution of the question connected with methodological and uniform approach to determinati...