Analytic philosophy - arguably the most important philosophical movement in the 20th century - has gained a new historical self-consciousness, particularly about it's own origins. The period between 1880 and 1930 saw the most important work of its founding figures (Frege, Russell, Moore, Wittgenstein) take root and flourish. The fifteen previously-unpublished essays in this collection explore different facets of this period, with an emphasis on the vital intellectual relationship between Frege and the early Wittgenstein.