#4. Wealth and Natural Riches.# We do not learn anything by reading that #political economy is the science of wealth#, unless we know what science is, and what wealth is. When one term is defined by means of other terms, we must understand these other terms, in order to get any light upon the subject. In the Primer of Logic I have already attempted to explain what science is, and I will now attempt to make plain what wealth is. Doubtless many people think that there is no difficulty in knowing what #wealth# is; the real difficulty is to get it. But in this they are mistaken. There are a great many people in this country who have made themselves rich, and few or none of them would be able to explain clearly what wealth is. In fact it is not at all easy to decide the question. The popular idea is that wealth consists of money, and money consists of gold and silver; the wealthy man, then, would be one who has an iron safe full of bags of gold and silver money. But this is far from being the case; rich men, as a general rule, have very little money in their possession. Instead of bags of money they keep good balances at their bankers. But this again does not tell us what wealth is, because it is difficult to say what a bank balance consists of; the balance is shown by a few figures in the bankers' books. As a general rule the banker has not got in his possession the money which he owes to his customers. Perhaps some one will say that he is beyond question rich, who owns a great deal of land. But this depends entirely upon where and what the land is. A man who owns an English county is very wealthy; a man might own an equal extent of land in Australia, without being remarkably rich. The savages of Australia, who held the land before the English took it, had enormous quantities of land, but they were nevertheless miserably poor. Thus it is plain that land alone is not wealth.