This book is the first volume in a new series that presents original texts by G. W. Leibniz accompanied by authoritative English translations on the facing pages. The volumes, which will be translated, annotated, and introduced by well-known Leibniz scholars, are a valuable resource for those interested in the works of this eminent seventeenth-century philosopher. De Summa Rerum is a selection of twenty-five papers written by G. W. Leibniz early in his career between December 1675 and December 1676. Unlike many of his other works, which were written for other people, Leibniz wrote these essays to clarify in his own mind the thoughts on such major philosophical issues as the philosophy of physics, and the nature of God and of the human mind. In these papers, Leibniz propounds many of the philosophical doctrines for which he is best known. This volume makes these important works available in English, many of them for the first time.