In three comprehensive volumes, Logic of the Future presents a full panorama of Charles S. Peirce's important late writings. Among the most influential American thinkers, Peirce took his existential graphs to be his greatest contribution to human thought. The manuscripts from 1895--1913, most of which are published here for the first time, testify the richness and open-endedness of his theory of logic and its applications. They also invite us to reconsider our ordinary conceptions of reasoning as well as the conventional stories told about the evolution of modern logic. This first volume of the series tells, for the first time, the full story of Peirce's 1896 discovery of the logic of Existential Graphs and its wider impact to his theory of diagrammatic reasoning. It also illustrates the abundant further developments and applications Peirce envisaged existential graphs to have to the analysis of mathematics, language, meaning and mind.