Charles Sanders Peirce (1839-1914) was an American philosopher, physicist, mathematician, and the founder of pragmatism. Despite his importance in the history of philosophy, a unified statement of his thought has been unavailable. With this publication, readers are offered the philosopher's only known, complete, and coherent account of his own work. Comprising a series of lectures given in Cambridge, Massachusetts, in 1898, "Reasoning and the Logic of Things" aims to provide an accessible and thorough introduction to Peirce's mature thought. Beginning with an explanation of the nature of philsophy, Peirce proceeds to illustrate his claim that mathematics provides the foundation of our logic and metaphysics. We find here the clearest formulation of an idea present in Peirce's thought since the 1860s, the distinction among three kinds of reasoning: induction, deduction, and retroduction. Then follows an introduction to Peirce's chief logical doctrines, as well as his attempts to provide a classification of the sciences, a theory of categories, and a theory of science. In conclusion, turning from "reasoning" to the "logic of things", Peirce called for an evolutionary cosmology to explain the reality of laws and described the kinds of reasoning he employed in developing this cosmology. At the urging of his friend William James, Peirce made an uncharacteristic effort in these lectures to present his ideas in terms intelligible to a general audience - those without advanced training in logic and philosophy. The introductory materials by Ketner and Putnam add to the volume's lucidity.