The philosophy of mathematics plays a vital role in the mature philosophyof Charles S. Peirce. Peirce received rigorous mathematical training from his fatherand his philosophy carries on in decidedly mathematical and symbolic veins. ForPeirce, math was a philosophical tool and many of his most productive ideas restfirmly on the foundation of mathematical principles. This volume collects Peirce'smost important writings on the subject, many appearing in print for the first time.Peirce's determination to understand matter, the cosmos, and "the granddesign" of the universe remain relevant for contemporary students of science, technology, and symbolic logic.