How it works
Credit is using a lender's coins now and paying later. Ruth could not pay Mae 6 coins for cloth until after the festival, so she used credit. It works in six written steps: ask, check, agree, use, bill, pay.
Ask for an account, a page in the bank's book with your name. The bank checks whether you paid back on time. You agree a limit, the most you can use at once, and a price: no extra if paid in full by the due day.
Use it: the bank pays the shop at once, and you owe the bank. At month's end the bill comes, with the amount and a due day. Then you pay, and the bank writes a tick in your record.
If the due day goes by, the bank adds a price and notes the late day. Credit is not magic: it is a promise, written down and kept.