The overtrading of some bold projectors in both parts of the United Kingdom was the original cause of this excessive circulation of paper money.

What a bank can with propriety advance to a merchant or undertaker of any kind, is not either the whole capital with which he trades, or even any considerable part of that capital; but that part of it only which he would otherwise be obliged to keep by him unemployed, and in ready money for answering occasional demands. If the paper money which the bank advances never exceeds this value, it can never exceed the value of the gold and silver which would necessarily circulate in the country if there was no paper money; it can never exceed the quantity which the circulation of the country can easily absorb and employ.

When a bank discounts to a merchant a real bill of exchange drawn by a real creditor upon a real debtor, and which, as soon as it becomes due, is really paid by that debtor, it only advances to him a part of the value which he would otherwise be obliged to keep by him unemployed and in ready money for answering occasional demands. The payment of the bill, when it becomes due, replaces to the bank the value of what it had advanced, together with the interest. The coffers of the bank, so far as its dealings are confined to such customers, resemble a water pond, from which, though a stream is continually running out, yet another is continually running in, fully equal to that which runs out; so that, without any further care or attention, the pond keeps always equally, or very near equally full. Little or no expense can ever be necessary for replenishing the coffers of such a bank.

A merchant, without overtrading, may frequently have occasion for a sum of ready money, even when he has no bills to discount. When a bank, besides discounting his bills, advances him likewise upon such occasions such sums upon his cash account, and accepts of a piecemeal repayment as the money comes in from the occasional sale of his goods, upon the easy terms of the banking companies of Scotland; it dispenses him entirely from the necessity of keeping any part of his stock by him unemployed and in ready money for answering occasional demands. When such demands actually come upon him, he can answer them sufficiently from his cash account. The bank, however, in dealing with such customers, ought to observe with great attention, whether in the course of some short period (of four, five, six, or eight months for example) the sum of the repayments which it commonly receives from them is, or is not, fully equal to that of the advances which it commonly makes to them. If, within the course of such short periods, the sum of the repayments from certain customers is, upon most occasions, fully equal to that of the advances, it may safely continue to deal with such customers. Though the stream which is in this case continually running out from its coffers may be very large, that which is continually running into them must be at least equally large; so that without any further care or attention those coffers are likely to be always equally or very near equally full; and scarce ever to require any extraordinary expense to replenish them. If, on the contrary, the sum of the repayments from certain other customers falls commonly very much short of the advances which it makes to them, it cannot with any safety continue to deal with such customers, at least if they continue to deal with it in this manner. The stream which is in this case continually running out from its coffers is necessarily much larger than that which is continually running in; so that, unless they are replenished by some great and continual effort of expense, those coffers must soon be exhausted altogether.

The banking companies of Scotland, accordingly, were for a long time very careful to require frequent and regular repayments from all their customers, and did not care to deal with any person, whatever might be his fortune or credit, who did not make, what they called, frequent and regular operations with them. By this attention, besides saving almost entirely the extraordinary expense of replenishing their coffers, they gained two other very considerable advantages.

First, by this attention they were enabled to make some tolerable judgment concerning the thriving or declining circumstances of their debtors, without being obliged to look out for any other evidence besides what their own books afforded them; men being for the most part either regular or irregular in their repayments, according as their circumstances are either thriving or declining. A private man who lends out his money to perhaps half a dozen or a dozen of debtors, may, either by himself or his agents, observe and inquire both constantly and carefully into the conduct and situation of each of them. But a banking company,