此时，银行开始登场。当前比较流行的做法是，国家通过中央银行【英格兰银行、美国联邦储备系统（Federal Reserve System）等】管理其财政，中央银行可能由政府拥有并控制，或政府在其中具有较大影响力，它们与国内的私营银行进行交易。中央银行是黄金供应（除了可能由国库持有的部分）的保管机构，并负责严格按照黄金比率发行该国的货币。私营银行则可以发放信贷（假定可兑换货币），而为控制私营银行的这一活动，私营银行必须在中央银行存有或习惯性存入一定比例的资金（存款）——国际惯例是10%到15%。因此，如果中央银行持有1美元等价黄金，便可以向下级机构发行2.50美元信贷，而从理论上来讲，下级机构又可以将其扩大到25美元的信贷，并向消费者发放，但这依然符合法律规定，且严格遵守了金本位制度。金本位制度规定，每一张纸币都可以兑换成黄金！
Gold Into Credit
Here banking enters the picture. The fashion of today is for a country to organize its finances by means of a central bank (Bank of England, Federal Reserve System, etc.) either owned, controlled, or largely influenced by its government and doing business with the private banks of the country. This central bank is the custodian of the gold supply (except what part might be held by the Treasury) and issues the country's currency, governed strictly by the gold ratio. The private banks of the country, however, may issue their own credit (presumably redeemable in currency), and to control this, each is required to keep, or has made a habit of keeping, an amount equivalent to a percentage of the money it owes (its deposits) with the central bank -- 10 to 15 per cent is the rule. Thus for the possession of $1.00 of gold, the central bank may issue $2.50 of credit to a lesser institution which, in turn may, theoretically, extend $25 worth of credit to a customer and still be within the law, abiding strictly by the gold standard which says that each and every paper dollar may be redeemed in grains of gold!
The exact methods of effecting this elasticity vary widely. In the U. S., we have our Federal Reserve System's twelve central banks, each lending money to member banks. At present, $1.00 of gold supports about $14 of credit. In Great Britain, £1 supports £19 of notes and credit. Less developed credit machinery allows less expansion.
Underlying all systems, however, is the central fact that each must have its supply of gold to support it (or currency based on gold, as in the Gold Exchange Standard). From which it becomes immediately apparent that, having split up the common supply, there may be a plethora of gold in the world and a shortage of it in one country. Which factor we would like you to file away for future reference (it will be discussed presently) and consider first the significance of this involved system of levers whereby $1.00 may be stretched to $25. Item: it is essentially a contrivance which substitutes paper for gold in the process of weighing values (the paper is defined as being exchangeable for gold but there isn't enough gold to exchange for it, hence paper is really used in the balance). Item: it is immensely convenient. Besides being handy, it accelerates the speed with which gold money changes hands (the velocity of money is another factor suggested here, to be taken up in turn), which makes it more effective. Item: observed casually, it appears the answer to gold famine alarmists. If gold production doesn't keep pace with commodity production, all the world has to do is to allow itself a little more credit. The U. S. only stretches $1.00 into $14 when its laws allow it to reach to $25; when it reaches $25, change the laws to let it touch $50. One catch is that whenever the world, or any part of it, does allow itself more credit, it may lose its self-confidence. The basic ratios of around 30 per cent to 40 per cent gold in reserve are, generally, fixed by law. But if the laws were repealed tomorrow, most of the nations of the world would make no move to take advantage of the respite, and any that did would be in danger of finding their credit vanishing. This country stretches $1.00 to $14, can stretch to $25. Yet if it raised the mark to $16 or $17 (still well within the legal limits), the cry of inflation might be raised. Herein we observe the cogwheel "public confidence" turning. Collectively, the world mutters in its beard that it "has had a lot of experience with inflated currency." Yet, obviously, all its currency is inflated. It's inflating it any more which bothers our people. The relation is, patently, far from absolute. The U. S. extends more credit than Brazil, yet its credit is better; it is better now than when in mid-19th century, it only stretched $1.00 to $4.00 or $5.00. Still, governments have given a good deal of concern to the problem of palming off paper for gold in a genteel way.
This section has dealt, characteristically, with the problem from the mechanical viewpoint -- how the machine might influence the credit. The converse is, of course, the larger conception. It is, essentially, man's confidence in himself and in his future that permits him, to extend himself credit. The machine is only a machine, man-made. Hence it would be quite proper to say that man's self-confidence, interpreted in credit, governs it. The part played by confidence, faith, or whatever you wish to label man's belief in himself, cannot be overemphasized.
There is still another, and very active, part of the machine over which governments and international committees have no direct control, and that is the extension of credit in trade. Every merchant, manufacturer, broker, or tradesman who gives a customer time to pay is really loaning his customer the money. The customer gets credit from the merchant instead of borrowing from his bank and paying cash.
At this point we had better pause to examine that least controllable and most mysterious of all elements in the machine, the velocity of money. The subject is apropos, for it is in the above last far-flung extension of credit by individuals that the velocity factor is especially potent. The principle advanced is simple: the same dollar bill, used twice, is as effective as two individual dollar bills; the same amount of gold reserve has done twice the work. The credit you extend to me in loaning me $10 is, far away across a sea of subtlety, linked to buried gold; but there is no link between that treasure and the number of times that $10 bill will be used. Nor the number of times the same amount of money in a bank may be checked against, if I pay you back with a check and you deposit it in the same bank and draw against it again. There has been much research done, and many theories have been advanced on the subject. The velocity seems to indulge in cycles "sympathetic to business," and the circulation may, in a single upswing, treble. This much is certain: the tendency is upward with the march of civilization, toward a higher velocity.
To review rapidly: the machinery for the use of gold as an instrument for valuing commodities spreads fan-wise from a base of gold. Central banks, banks of issue, etc., grant credit (paper money, etc.) up to not more than two and one-half times their gold reserve; private banks, recipients of this credit, grant further credit based on it; individuals, in proportion to their dispositions and financial security, give one last-and powerful-fling to the value of those precious grains in the closely guarded vault. Through all of which the "velocity of circulation" factor enters, and no man knows, for certain, just how much work those same grains may eventually accomplish.
Leaving the consideration of the extension of the total actual credit already created on the world's gold, let us return, as we promised, to the proposition that ills may arise as readily from shifting the gold we have as from any general shortage. It is written that each country committed to a gold standard must have its own gold to back up its own bank notes. But the idea of a common gold standard entails the free passage of gold from country to country in settlement of international balances, in stabilizing the world's moneys in terms of gold. Nations must pay their debts in gold (if asked) and, allowed to choose its home, free gold will always go where (1) it will be safest and (2) make the most money. A run of commercial bad luck, then, means a tendency on the part of a nation's gold to run where it can make more money or feel safer -- and in payment of the money the nation owes.
(Here we have taken the easiest course in describing the machine and sketched in a part [the reason for gold movements] by the use of a theory, a popular one, but still a theory. Many and elaborate are the explanations advanced for why gold moves. Whichever is right, gold does move, from nation to nation, wandering.)
Now there is no panacea for diminishing gold reserves -- no handy cure-all for what is often a symptom of economic distress. By far the happiest way to keep gold at home is to be more prosperous than your neighbor. But if, as a nation, you can't manage this, you may be tempted to resort to artificial (and temporary) expedients. And a common artificial respirator of gold reserves among perhaps half-dozen leading countries is the raised rediscount rate. It works thus: the central bank announces that it will charge more interest for the money it loans (in "rediscounting" obligations), hence other banks must charge higher rates, and money throughout the land becomes dear. The gold which was so anxious a minute before to get somewhere else now may prefer to stay at home to benefit by these higher rates. The disadvantages of this system are that it entails charging your own countrymen more money for their loans, handicaps them, and may eventually lower their scale of living. Also, you may be overbid and have to raise again. If you don't care to raise your rediscount rate, you may place some kind of an embargo on outgoing gold-tax exported capital, or only deliver gold metal in an unacceptable form, i.e., make it inconvenient for export and so slow the process -- or you can up and make it against the law to export gold, a drastic step almost always taken in war but extremely disturbing to peace-time commerce because it removes the guarantee of gold redemption, at least in foreign parts.
Another method of expanding and n contracting credit which is worth your knowing about might be titled "Open Market Operations of Central Banks," and it is used, principally, by the U. S. and England. The idea is ingenious. When the central bank wants to make money easier to get, it goes out into the market and buys securities. For them, the bank gives a check which soon finds its way back to the central institution as a deposit, credited to the account of some member bank. The result is an increase in the member bank deposits with the central bank, which allows the former to extend some ten times as much credit. The central bank has only to maintain its customary percentage of gold behind the deposit. Thus large credit is made available with little metal, is literally forced on the market. Reverse the process, and you have the central bank selling securities, lowering member bank balances, and tightening credit.
Do not let the comparative simplicity of this exposition deceive you. The physical operation is complicated, the issues involved are subtle, and the use or abuse of open market operations is hotly disputed.