It would seem, moreover, that political economists, especially in Germany, have attached too much importance to putting formal bounds to their special science. Why not rather follow the example of the students of nature who care little whether this or that discovery belongs to physics or chemistry, to astronomy or mathematics, provided, only, very many and important discoveries are made?(152) Section XXI. What Political Economy Treats Of. Political Economy treats chiefly of the material interests of nations. It inquires how the various wants of the people of a country, especially those of food, clothing, fuel, shelter, of the sexual instinct etc., may be satisfied; how the satisfaction of these wants influences the aggregate national life, and how in turn, they are influenced by the national life. (Gospel of Matth., 4, 4.) This alone suffices to enable us to estimate the importance of the science. The relation of virtue to wealth is likened by Bacon to that of an army to its baggage. In Xenophon’s opinion, wealth is really useful only to him who knows how to make a good use of it. From an economic point of view, the happiest man is he who has accumulated most, honorably, and used it best.(153) That, even in a material sense, the intellect of a people is their most important element, is evident from the example of the Chinese, who were so long acquainted with printing, powder, and the mariner’s compass, without, by their means, attaining to intelligent public opinion, forming a good army, or coming to an understanding of the art of navigation, to any great extent. The undervaluing of economic matters, for which ages of inferior cultivation, our own middle ages for instance, are now praised and now blamed, was really a rare exception even during these ages.(154) Other kinds of acquisition and enjoyment then occupied the foreground; but there never was a time, when gain and enjoyment in general were not favorite objects of pursuit, and held in high esteem. The physical wants of uncultured men cry out much louder than intellectual ones. (§ 2, 14.)(155) On the other hand, in over-cultivated ages, when decay begins, an over-estimation of material things is wont to become general.(156) The mere servants of mammon, whether as political economists or as private individuals, may see their depravity faithfully reflected in communism as in a mirror. We should not overlook the fact that it is with whole nations as with the individual man who amasses his own fortune. He reaches the culminating point of his wealth generally after he has passed the prime of life. The most flourishing period of a nation’s existence is wont just to precede its decay, and to introduce it.(157) Hence, here nothing could be more untrue, as Macchiavelli has remarked, than the general opinion that money is the sinew of war.(158) Chapter III. The Methods Of Political Economy.