1. _From the twelfth to the sixteenth centuries the sale and purchase of rent-charges was the most general form of borrowing and lending wealth._ A rent-charge in the Middle Ages was a definite income that was to be paid out of the rents of an estate, business house, manor, etc. The property was said to be "charged" with the payment of that income, and some estates were passed on for generations from father to son charged with a certain rent. It was thus possible for the owner of money to buy a rent-charge, either one that had been created a generation before, or a new one created by some landowner for the especial purpose of borrowing money to go on a crusade or of improving his estate or of investing in other business. The transaction took this form: the purchaser of the rent-charge paid a sum of money, called the capital sum, and obtained in return a rent-paper entitling him to receive permanently a given income. The house or land was security for the debt. The seller gave up the right to the rent as it came in year by year, and received in return a capital sum in hand. Generally he had the right to repay the sum whenever he wished and thus extinguish the rent-charge. Logically viewed, the purchaser bought an equitable part of the income, therefore an equitable part of that rent-bearing wealth. In effect it was just like a loan except that the purchaser of the rent-charge could not demand the repayment of his money. He could, however, sell the rent-charge when he wished to get his capital out. Gradually it became usual to sell and transfer rent-papers just as is done to-day with mortgages and bonds. Rent-papers thus came in the fifteenth century to be negotiable paper in somewhat general use. There was a rise and fall of the value of the rent-paper with changes in the demand for investment in rent-charges or with changes in the security. [Sidenote: Rent-charges were a convenient investment in medieval cities]