These volumes contain explanations of the development of one essential phase of human civilization -- the development of systematized positive knowledge. The history of religion, in strict
chronological order, is discussed at length, since science and religion were inseparable. The history of music and the early history of philology are also considered. The main object is to explain the progress of
scientific thought with the gradual development of human consciousness -- that deliberate tendency to understand and to increase our part in the cosmic evolution.