After testing all these principles experimentally for a considerable time, the people on the island came to see that the possession of money was the consequence rather than the cause of wealth; and that, except under special circumstances and conditions, the rate of interest depends on the abundance or scarcity of that part of the capital of a community which does not consist of money; and that it can not be permanently lowered by any increase in the quantity of money. [36] In this way, through the school of hard experience, the people on the island came gradually to understand that there were certain economic truths which had got to be accepted and lived up to in order to insure either individual or national prosperity. They came to understand that property is a physical actuality, the result of some form of labor; that capital is that portion of the results of production which can be reserved and made available for new and further production; that money is an instrumentality for facilitating the distribution and use of capital and the interchange of products and services; that production alone buys production; that when one buys goods with a paper representative or symbol of money, the goods are not paid for until the representative is substituted by a value of some sort in labor, or money, or some other commodity; and, finally, that a country and its inhabitants increase in wealth or abundance by increasing their products, rather than by inordinately multiplying machinery for the exchange of products. They also saw that the promises to pay which they had been using and regarding as money were debts; and that debts, as well as all other forms of title, are but shadows of the property they represent; and that, in endeavoring to all get rich by first creating debts, then calling the debts money, and the money wealth, they had been led, successively, into speculation, extravagance, idleness, and impoverishment; and, like the dog in the fable, which let go of the meat in crossing a stream for the sake of grasping its shadow, they had lost much of real wealth resulting from previous industry by trying to make the shadow of wealth supply the place of its substance. Coming to gradually realize, also, that one of the first requisites for an increase of trade was that confidence should exist between the buyer and the seller, but that such confidence never would exist so long as the representatives of value, or other intermediate agencies made use of for facilitating exchanges, were of an uncertain, fluctuating character, they also came finally to the conclusion that there was no economy in using cheap money; or, in other words, that the loss and waste inevitably resulting from the use of poor tools (money being a tool) was many times in excess of the interest accruing from any increased cost of good tools. So reasoning, gold, or undoubted promises to pay gold, gradually came once more into use as money on the island.