But when a very great number of men entrust their money in this fashion, and do not specially stipulate that it should be left untouched, when there is a sort of silent understanding that, if whenever they want it, the money will be forthcoming, then they do not ask too closely what has been done with the whole of the sum in the custodian’s hands. For if _very many_ people are thus “banking” their money with one safe custodian only a certain proportion will _at any one time_ want their money, and the rest can be used without danger of the “banker’s” failing to meet any particular demand. Thus banking, that is, the use of other peoples’ money, arises and becomes a natural process because it is of mutual advantage. The Banker can earn profits with that average amount of money which always remains in his hands, the depositors have their money safely looked after and may even share in the profit. A hundred men, let us say, have given £1,000 each into the hands of such a custodian, who has come to be called their “Banker.” The total sum of money in this man’s hands is £100,000. It is found in practice, over the average of a number of years, that this hundred men do not “draw” upon (that is, ask for their money to be paid out to them by) their banker more than to the extent of, let us say, £100 every month each, and it is also found that, while they need this £100 to pay wages or bills or what not, they also come back with the money they earn (say, £120 per month, on the average) and give it back to their banker for safe keeping. In several years of this practice the banker discovers that he must have about 100 times £100, that is £10,000, in free cash to meet the demands upon him, and that he gets rather more put into his custody in the same period of a month, year in and year out. It follows that he always has about £90,000 in gold doing nothing the whole time. He says to himself: “Why should I not use this money to buy instruments of production--ships or ploughs, or machinery or what not--and produce more wealth? It will not hurt those who have deposited it with me, for I have found that, _on the average_, they never want more than a tenth of their money out at the same time (and they are also perpetually paying in more money to me--so that they and I are quite safe), and if I make a good profit by the use of the things I shall have bought with this £90,000 I can offer them part of the profit. So we are both benefited.”