Readers are invited to read a book by the German philosopher August Messer on the theory of knowledge. The author sought to give a truly "introduction," pursuing the goals of a possibly clear and understandable presentation. The book comprehensively acquaints the reader not only with the basic concepts of the theory of knowledge and with the historical fates of staging and solving various philosophical problems, but also with the methods of philosophical thinking. At one time, which, according to critics, has become one of the best introductions to the theory of knowledge, the book has not lost its relevance and can serve as a guide to the history of epistemology. Recommended to philosophers, historians and methodologists of science, as well as anyone interested in the problems of the theory of knowledge.