Today, when you receive a check, you consider yourself paid. Indeed, for tax purposes, you swear to it. That's like swearing that a gift-certificate is the gift itself. No, you'll get bank notes which are not redeemable in anything, and are, obviously, not money in themselves. We have divorced money from reality.
Credit is a creation of the banking system.
If the numbers on a check are simply written there by the issuer, the check may be bad unless the issuer's account at the bank contains a number at least at large, written by the banker. Those written by the rest of us are doodles, or, if we attempt to obtain goods or services with them, an example of check kiting, a crime. What distinguishes a good check from a bad is, therefore, partly a matter of geography. Of course, the fact that it is allowable to tender a non-redeemable note doesn't mean that one is obligated to accept it, although if nothing else is offered, or can be offered, it amounts to that. Even checks, however, have become cumbersome.