I Owe You
Ideally debts and credits are ratified by “gentlemen’s agreement”, that is, “signed” with a handshake. But when things are less ideal or rather when pacts are just too numerous, they have to be traceable.
So debts and credits begin to be documented by what is called an “I Owe You” (sometimes also referred to as an IOU); it can have such forms as a signed piece of paper, a registry entry, or something like that; the law regulates it as such and calls it promissory note. Any I Owe You is based on what basically constitutes society itself – the agreement: if any of its forms has any value, it is the value most of the individuals agree upon.
As we go ahead, bear in mind what an I Owe You is: for the debtor it represents the obligation to give to a creditor a given amount of the debtor’s product, for the creditor it represents the right to claim that product from that debtor, and all that is guaranteed by the social agreement that will enforce it.