182 Compare this whole chapter with _Roscher_, Leben Werk und Zeitalter des Thukydides, 1842, pp. 25, 239-275; _Roscher_, Grundries zu Vorlesungen über die Staatswirthschaft nach geschichtlicher Methode, 1843, preface; _Roscher_ Geschichte der Nat. Œk. in Deutchland (1874), 882 f., 1017 seq., and D. Vierteljahrsschrift, ff. See also _J. Kautz’s_ learned and accurate Theorie und Geschichte der N. Œkonomik, vol. I, 1858, II, 1860. I find no real contradiction between the views here expressed and those of _Kautz_, when he (I, pp. 313 ff.) introduces history and ethico-practical reason with their ideals as sources of Political Economy, to the end that the science may be something more than simply a picture, namely, a model of economic life. Apart from the fact that it is only the ethico-practical reason that can understand history at all, the ideals of a period constitute one of the most important elements of its history. The aspirations of an age find in them their best expression. The historical political, economist as such, is certainly not disinclined to form plans of reform, nor can it be said that he is not adapted to the performance of such a task. Only, he will scarcely recommend his reforms as absolutely better than what they are intended to supplant. He will confine himself to showing that there is a want which may, probably, be best satisfied by what he proposes. See _Sartorius_, Einladungsblätter zu Vorlesungen über die Politik, 1793. 183 “There is a book which youth may use to grow old, and the old to remain young—History.” (_K. S. Zaccharia_). 184 Especially when natural science begins to be “a practical science.” (_L. Stein_). 185 The difference between the broader and narrower sense of production, corresponds essentially with that of gross and net income (§ 145). Compare also §§ 206, 211 ff. _ 186 Von Mangoldt_ distinguishes the coming into existence of free values of the production undertaken for an economic purpose. (Grundriss, 9.) _ 187 Gioja_, Nuovo Prospetto delle Scienze economiche (1815), I, 49 ff. Besides positive production, there is a latent production, which prevents the decay of goods. It is not possible to make as exact an estimate of the latter as of the former; and much more depends in the latter case than in the former on continuity and proper extension. Hence, latent production is especially a state concern. (_Knies_, Telegraph als Verkehrsmittel, 1857, 232.) 188 See _Schäffle_, in the Tübinger Univ. Programm, September 27, 1862, on the disastrous effect on the community of idleness. The leading of a happy life the Greeks called very appropriately, εὐπράττειν (_Garve_).