Sismondi’s conception of economic method is incontestably just so long as the economist confines himself to the discussion of practical problems or attempts to gauge the probable effects of a particular legislative reform or is unravelling the causes of a particular event. But should the economist wish to picture to himself the general aspect of the economic world, he cannot afford to neglect the abstract method, and Sismondi himself was forced to have recourse to it. It is true that he used it with considerable awkwardness, and his failure to construct or to discuss abstract theories perhaps explains his preference for the other method. At any rate it does partly explain the keen opposition which his book aroused among the partisans of what he was the first to call by the happy title of the “Orthodox” school. But to imagine anything more confused than the reasonings by which he attempts to demonstrate the possibility of a general crisis of over-production is difficult.[381] For his point of departure he takes the distinction between the annual revenue and the annual production of a country. According to him the revenue of one year pays for the production of the following.[382] Accordingly, if the production of any one year exceeds the revenue of the previous year a portion of the produce will remain unsold and producers will be ruined. Sismondi reasons as if the nation were composed of agriculturists who buy the manufactured goods they need with the revenue received from the sale of the present year’s crop. Consequently if manufactured products are superabundant, the agricultural revenue will not be enough to pay a sufficient price. But within the argument there lurks a twofold confusion. At bottom a nation’s annual revenue is its annual produce, and the one cannot be less than the other. Moreover, it is not the produce of two different years that is exchanged, but the various products of the same year, or rather (for this subdivision of the movements of the economic world into annual periods has no counterpart in actual life) it is the different products created at every moment that are being continually exchanged, thus constituting a reciprocal demand for one another. At any one moment there may be too many or too few products of a certain kind, resulting in a severe crisis in one or more industries. But of every product, at one and the same time, there can never be too much. McCulloch, Ricardo, and Say victoriously upheld this view against Sismondi.[383]