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Gottlob Frege (1848-1925) is known as the father of analytic philosophy and the founder of modern logic. In 1902, just when the publication of Frege's logical system was nearing completion, Bertrand Russell discovered a famous contradiction in it, which Frege was never able to repair. This disaster overshadowed the remaining years of Frege's life, and he became increasingly bitter that the larger worlds of mathematics and philosophy had failed to recognize his achievements. During these later years, Rudolf Carnap (1891-1970), soon to become the philosophical leader of the Vienna Circle and of logical empiricism, was a student of Frege's at the University of Jena, and took detailed and accurate shorthand notes on three courses he took with Frege. These notes, the only surviving record of Frege's lectures, are reproduced here in their original German, with facing translations, detailed commentary, as well as an introduction by Gottfried Gabriel, the leading German Frege scholar. They reveal how Frege sought to shore up his logical system in the face of Russell's contradiction, and how he integrated his later doctrine of sense and reference into his exposition of logic. They also offer unique insight into Frege's influence on Carnap.