The Wealth of Nations by Part 2 Chapter 2 Page 67

every dealer in the shape of money, whether paper or coin, and continually going from him in the same shape. If the advances of the bank had commonly exceeded this part of his capital, the ordinary amount of his repayments could not, within moderate periods of time, have equalled the ordinary amount of its advances.

The stream which, by means of his dealings, was continually running into the coffers of the bank, could not have been equal to the stream which, by means of the same dealings, was continually running out. The advances of the bank paper, by exceeding the quantity of gold and silver which, had there been no such advances, he would have been obliged to keep by him for answering occasional demands, might soon come to exceed the whole quantity of gold and silver which (the commerce being supposed the same)