Gottlob Frege (1848–1925) is well known to everyone interested in logic and philosophy, and his Begriffsschrift (1879) is considered the work which began the era of modern mathematical logic. Ernst Schröder (1841–1902) is in turn best remembered for his monumental Vorlesungen über die Algebra der Logik (1890–1905) which is the culmination of the Boolean tradition in the algebra of logic. Although Schröder and Frege were mathematicians writing primarily for a mathematical audience, they both attempted to reach philosophers as well. Schröder explicitly addressed his writings to both mathematicians and philosophers (1877, p. v; 1890, p. vi). Frege published most of his papers in philosophical journals and wished that logicians would accept his innovations (1879, p. xiii). Yet, despite their efforts to attract the attention of contemporary German philosophers, both Frege and Schröder remained isolated figures whose writings were either strongly criticized or completely neglected. Schröder managed to generate some interest in his ideas, but Frege's influence remained very limited for a long time. Frege's ideas began eventually to have an impact in Germany through Russell's The Principles of Mathematics (1903).