Schopenhauer's Essay on the Fourfold Root of the Principle of Sufficient Reason (Fourth Edition, Edited by FrauenstÄdt. The First Edition appeared in 1813).

This essay is divided into eight chapters. The first is introductory. The second contains an historical review of previous philosophical doctrines on the subject. The third deals with the insufficiency of the previous treatment of the principle, and prescribes the lines of the new departure. The fourth, fifth, sixth, and seventh treat of the four classes of objects for the subject, and the forms of the principle of sufficient reason which respectively characterise these classes. The eighth contains general remarks and results. It will be convenient to summarise these chapters severally.