Why an apple could count as payment
Money works when people accept something in exchange for goods or to settle what they owe. If metal coins are hard to come by, a useful, familiar product can fill that role locally. An apple has value because someone can eat it, cook with it, or trade it onward—not because it carries an official stamp.
That makes it a form of commodity money: an item whose usefulness gives it value. For a debt to be settled with apples, creditor and debtor must agree on how many apples count as payment. The arrangement is practical only while other people are willing to accept them, too.
The trouble with saving something that spoils
Coins can sit in a box without changing much. Apples cannot. Their condition worsens with time, so an apple kept for later may become worth less—or worthless—before it can be spent. A pile of them might function as savings, but only temporarily: the owner has to find a buyer or use them before decay takes away their value.
That deadline changes the bargain. The holder may be pushed to trade quickly, even if a better exchange might have been possible later. A perishable payment stores value only for as long as it remains edible. So an apple could clear an obligation and briefly serve as a reserve, while making time itself part of the cost of holding money.
