 2 of the "Grundgesetze" was about to go to press in 1903, showing that Russell's paradox could be derived from Frege's Basic Law V. It is easy to define the relation of "membership" of a set or extension in Frege's system; Russell then drew attention to "the set of things "x" that are such that "x" is not a member of "x"".The system of the "Grundgesetze" entails that the set thus characterised "both" is "and" is not a member of itself, and is thus inconsistent.Frege wrote a hasty, last-minute Appendix to Vol.