consequence of a difference of education, position in life etc., all equally well equipped, skillful and free in the matter of economic production and consumption, is one which, as Ricardo and von Thünen have shown, must pass as an indispensable stage in the preparatory labors of political economists. It would be especially well, when an economic fact is produced by the cooperation of many different factors, for the investigator to mentally isolate the factor of which, for the time being, he wishes to examine the peculiar nature. All other factors should, for a time, be considered as not operating, and as unchangeable, and then the question asked, What would be the effect of a change in the factor to be examined, whether the change be occasioned by enlarging or diminishing it? But it never should be lost sight of, that such a one is only an abstraction after all, for which, not only in the transition to practice, but even in finished theory, we must turn to the infinite variety of real life.(167) There are two important inquiries in all sciences whose subject matter is national or social life: 1. What _is_? (What has been? How did it become so? etc.) 2. What _should be_? The greater number of political economists have confounded these questions one with the other, but not all to the same extent.(168) When a careful distinction is made between them, the contrast between the (realistic) physiological or historical, and the idealistic methods is brought out.(169) Section XXIII. The Idealistic Method. Any one who has read a goodly number of idealistic works treating of public economy (the state, law etc.) cannot have failed to be struck by the enormous differences, and even contradictions, as to what theorizers have considered desirable and necessary. There is scarcely an important point which the highest authorities may not be cited for or against. We must not close our eyes to this fact. “The giddiness that comes from contemplating the depths of knowledge is the beginning of philosophy, as the god Thaumas was, according to the fable, the father of Iris.” (_Plato._) In a precisely similar manner, the student of public economy (politics, the philosophy of law etc.) must familiarize himself with the variations that have taken place in what men, at different periods of history, have required of the state and public economy, until he is lost in wonder at the contemplation. Section XXIII. The Idealistic Method. (Continued.)