Pure Sociology is a synthesis of Wards sociological thought; his next to last book. Lester F. Ward (1841-1913) worked as a government geologist and paleontologist from 1881 to 1906, when he became professor of sociology at Brown. One of the first and most important of American sociologists, Ward developed a theory of planned progress called telesis, whereby man, through education and development of intellect, could direct social evolution. Ward was eulogized at his death as one of the last giants of nineteenth-century sociology, and many of his ideas - the primacy of artificial over natural forces in the development of human society, the psychological rather than the biological basis of human life, and the stress on process and function rather than on structure in the study of society - provided leads for the researchers in sociology who succeeded him. The emergence of the modern welfare state and the involvement of professional sociologists in the practical problems of politics, poverty, and race represent a kind of vindication of his work.