Reprinted in R. A. Gordon and L. R. Klein (eds.), Readings in Business Cycles , Homewood, Irwin, 1965, pp. 366-378; reprinted in Bobbs-Merrill Reprint Series in Economics , Econ-167. This article has been identified as a Citation Classic, based on 195 citations in the Social Sciences Citation Index , in Current Contents , Vol. 14, No. 40, October 4, 1982. The paper was chosen as one of the Top 20 papers published in the first 100 years of the American Economic Review by Kenneth J. Arrow, B. Douglas Bernheim, Martin S. Feldstein, Daniel L. McFadden, James M. Poterba, and Robert M. Solow (2011), “100 Years of the American Economic Review: The Top Twenty Articles,” American Economic Review, Vol. 101, February, pp. 1-10. Investment 1, ch. 1, pp. 1-16.