a human activity (White 1947). This encounter proved fateful, and Wilder's research interests underwent a major change, towards the foundations of mathematics. This change was foreshadowed by his 1944 article "The nature of mathematical proof," and heralded by his address to the 1950 International Congress of Mathematicians, titled "The cultural basis of mathematics," which posed the questions: "How does culture (in its broadest sense) determine a mathematical structure, such as a logic?" "How does culture influence the successive stages of the discovery of a mathematical structure?" In 1952, he wrote up his course on foundations and the philosophy of mathematics into a widely cited text, Introduction to the foundations of mathematics. Wilder's Evolution of mathematical concepts. An elementary study (1969) proposed that "we study mathematics as a human artifact, as a natural phenomenon subject to empirical observation and scientific analysis, and, in particular, as a cultural phenomenon understandable in anthropological terms." In this book, Wilder wrote: "The major difference between mathematics and the other sciences, natural and social, is that whereas the latter are directly restricted in their purview by environmental phenomena of a physical or social nature, mathematics is subject only indirectly to such limitations. ... Plato conceived of an ideal universe in which resided perfect models ... the only reality mathematical concepts have is as cultural elements or artifacts." Wilder's last book, Mathematics as a cultural system (1981), contained yet more thinking in this anthropological and evolutionary vein. Wilder's eclectic and humanist perspective on mathematics appears to have had little influence on subsequent mathematical research. It has, however, had some influence on the teaching of mathematics and on the history and philosophy of mathematics. In particular, Wilder can be seen as a precursor to the work of Howard Eves, Evert Willem Beth, and Davis and Hersh (1981). Wilder's call for mathematics to be scrutinized by the methods of social science anticipates some aspects of Where Mathematics Comes From, by George Lakoff and Rafael Nunez. For an introduction to the limited anthropological research on mathematics, see the last chapter of Hersh (1997). Bibliography Books by Wilder: 1949. Topology of Manifolds. 1965 (1952). Introduction to the foundations of mathematics. 1969. Evolution of mathematical concepts. An elementary study. 1981. Mathematics as a cultural system. () Biographical: Raymond, F., 2003, " Raymond Louis Wilder" in Biographical Memoirs National Academy of Sciences 82: 336–51. Related work cited in this entry: Philip J. Davis