This book, published in two volumes called "books" by the author, is a treatment of everything from the origin of our ideas to how they are to be divided. It includes important statements of Scepticism and Hume's experimental method. Part 1 deals with the nature of ideas. Part 2 deals with the ideas of space and time. Part 3 deals with knowledge and probability. Part 4 deals with skeptical and other systems of philosophy, including a discussion of the soul and personal identity.