just before his death in Geneva, Switzerland on 19 August 1923. Sociology Pareto's later years were spent in collecting the material for his best-known work, Trattato di sociologia generale (1916) (The Mind and Society, published in 1935). His final work was Compendio di sociologia generale (1920). In his Trattato di Sociologia Generale (1916, rev. French trans. 1917), published in English by Harcourt, Brace in a four-volume edition edited by Arthur Livingston under the title The Mind and Society (1935), Pareto developed the notion of the circulation of elites, the first social cycle theory in sociology. He is famous for saying "history is a graveyard of aristocracies". Pareto seems to have turned to sociology for an understanding of why his abstract mathematical economic theories did not work out in practice, in the belief that unforeseen or uncontrollable social factors intervened. His sociology holds that much social action is nonlogical and that much personal action is designed to give spurious logicality to non-rational actions. We are driven, he taught, by certain "residues" and by "derivations" from these residues. The more important of these have to do with conservatism and risk-taking, and human history is the story of the alternate dominance of these sentiments in the ruling elite, which comes into power strong in conservatism but gradually changes over to the philosophy of the "foxes" or speculators. A catastrophe results, with a return to conservatism; the "lion" mentality follows. This cycle might be broken by the use of force, says Pareto, but the elite becomes weak and humanitarian and shrinks from violence. Among those who introduced Pareto's sociology to the United States were George Homans and Lawrence J. Henderson at Harvard, and Paretian ideas gained considerable influence, especially on Harvard sociologist Talcott Parsons, who developed a systems approach to society and economics that argues the status quo is usually functional. The American historian Bernard DeVoto played an important role in introducing Pareto's ideas to these Cambridge intellectuals and other Americans in the 1930s. Wallace Stegner, in his biography of DeVoto, recounts these developments and says this about the often misunderstood distinction between "residues" and "derivations": "Basic to Pareto's method is the analysis of society through its non-rational 'residues,' which are persistent and unquestioned social habits, beliefs, and assumptions, and its 'derivations,' which are the explanations, justifications, and rationalizations we make of them. One of the commonest errors of social thinkers is to assume