A book by the famous German philosopher and teacher Friedrich Paulsen, dedicated to the analysis of the main issues of philosophy. In the first part of the book, the author examines the problems of metaphysics, which include ontological and cosmological-theological problems. The second part covers the problems of the theory of knowledge - the problem of essence, or the relationship of knowledge to reality, and the problem of the origin of knowledge. Presenting philosophical problems in their development, the author not only cites their possible solutions proposed in the history of philosophy, but also seeks to substantiate the solution that seems correct to him. The work also contains a brief overview of ethical issues. F. Paulsen's book became so popular that in Germany alone it went through twenty-four editions until 1914; was repeatedly translated into many languages, including Russian. Recommended for philosophers, historians of philosophy, students and teachers of philosophical faculties and all interested readers.