Banks grew out of a practice by gold smiths and silver smiths, who, for a small price, accepted deposits for safekeeping. When they became lending institutions, their earliest rule was to keep almost 100% of cash reserves against their loans, so that they would not be caught short if most of their depositors decided to withdraw their money at the same time.
而同样的道德观也适用于机构债务。银行产生于金银匠人的实践之中，人们只需要支付一笔小钱就能把金银安全寄存在他们那里。而当这些人演变成借贷机构时，最早的规章就是要保证有100%的现金储备，以便在大多数客户同时决定取出存款时不至于无款可付。