Geach is best known for his contributions to theoretical philosophy: Most of his more than one hundred papers and a dozen books are on logic, philosophy of language and metaphysics. But he also made significant contributions to ethics. Particularly influential were a series of short metaethics papers, which are small masterpieces, both in terms of philosophical content and style. In usually less than ten pages, Geach delivers sharp analyses and powerful objections against influential schools. His arguments are always so clear and his examples so simple that they leave the reader wondering why no one before Geach detected the problems he points out.