R. A. Fisher is perhaps best known for his influential theoretical contributions to the ‘Evolutionary Synthesis’ of the 1930s and 1940s in which biometry was reconciled with Mendelism. It is no accident, I believe, that when historians discuss the ‘Synthesis’, the names R. A. Fisher, Sewall Wright and J. B. S. Haldane are nearly always given in that order. Fisher's 1918 paper ‘The correlation between relatives on the supposition of Mendelian inheritance’ suggested that biometry, which emphasized the distribution of characters based on continuous variation, and Mendelism, which emphasized discontinuous characters, were compatible and could be united to study evolutionary change. If one considered large numbers of discontinuous, Mendelian characters, then statistical biometrical analysis could be conducted. Thus, Fisher argued, biometry and Mendelism need not oppose each other.