"The History of Philosophy is the exposition of philosophical opinions and of systems and schools of philosophy. It includes the study of the lives of philosophers, the inquiry into the mutual connection of schools and systems of thought, and the attempt to trace the course of philosophical progress or retrogression. The nature and scope of philosophy furnish reasons for the study of its history. Philosophy does not confine its investigation to one or to several departments of knowledge; it is concerned with the ultimate principles and laws of all things"--Introduction.