Charles Sanders Peirce (1839–1914) was at once a chemist, astronomer, geodesist, logician and philosopher. He spent thirty years measuring the Earth’s gravity for the United States Coast Survey, created, independently of Frege, a notation for the quantifiers of logic and, in whatever hours were left, built the most influential theory of signs of the twentieth century. He died poor, in a house in Pennsylvania, leaving tens of thousands of manuscript pages that are still being edited today.