ABSTRACT
A "crisis" in the technical sense—i.e., a turn from prosperity to depression—is usually (but not always) accompanied by an acute "crisis" in the ordinary sense. The business cycle in the general sense may be defined as an alternation of periods of prosperity and depression, of good and bad trade. This definition is, however, provisional, for it is obviously too wide. It covers more than the business cycle in the technical sense of business-cycle theory. The economic cycle in which authors are primarily interested is that alternation of relatively prosperous and depressed times, together with all the concomitant changes in all parts of the economic system, which extends over the period of three to twelve years. This movement authors call the business cycle proper. A combination of the three indices—employment, real income consumed and real income produced—can be regarded as the criterion of the existence, and measure of the degree, of prosperity and depression and changes in the same.
