Economic Activity has its origins in a course of lectures given since 1950 to first-year undergraduates at the University of Adelaide. That course was originally given by P. H. Karmel; in later years the other two co-authors inherited it. Little attention was paid to financial factors in the first-year course. A second-year course of macro-economics (given on several occasions by R. H. Wallace) was built upon the first course, and in this the inter-relationships between the financial and production sectors of the economy were considered in detail. The second-year course was set in the context of the particular institutional framework of the Australian economy, and students were introduced to the relevant statistical material. The book draws upon material from both courses, but the discussion of the financial sector is essentially theoretical.