The Wealth of Nations by Part 4 Chapter 3 Page 25

credit would lose this premium. As a shilling fresh from the mint will buy no more goods in the market than one of our common worn shillings, so the good and true money which might be brought from the coffers of the bank into those of a private person, being mixed and confounded with the common currency of the country, would be of no more value than that currency from which it could no longer be readily distinguished. While it remained in the coffers of the bank, its superiority was known and ascertained. When it had come into those of a private person, its superiority could not well be ascertained without more trouble than perhaps the difference was worth. By being brought from the coffers of the bank, besides, it lost all the other advantages of bank money; its security, its easy and safe transferability, its use in paying foreign bills of exchange.