This 1931 book was written to replace The Elementary Principles of Roman Law, but it is not a second edition of that book. It is more systematic in plan: it aims at giving a central view of the different institutions of the Private Law and of the notions which underlie them. But its purpose is the same: its is for the use of students who have read the Institutes and little more, and it is intended to stimulate rather than to inform. It will still be of interest today.