Economies of scale. It is basically as easy for me to produce 20 sheets of paper as to produce 1 ; after paying the set up costs the marginal costs are much smaller in comparison. So all in all I would rather specialize in paper-making, have somebody else specialize in pencil-making, then trade.
Investment. often I need A LOT of capital to get something started, more than I could reasonably accumulate over a lifetime. So I would rather trade the starting capital for IOUs I will get from profit.
Insurance. I may have a particularly bad harvest this year and a very good one the next one, while my neighbour might have the opposite problem. All in all I would rather we pool our harvests each year, so that we can have food both years. So we are “trading” part of our harvest for insurance.
Other magical powers of trade:
Economies of scale. It is basically as easy for me to produce 20 sheets of paper as to produce 1 ; after paying the set up costs the marginal costs are much smaller in comparison. So all in all I would rather specialize in paper-making, have somebody else specialize in pencil-making, then trade.
Investment. often I need A LOT of capital to get something started, more than I could reasonably accumulate over a lifetime. So I would rather trade the starting capital for IOUs I will get from profit.
Insurance. I may have a particularly bad harvest this year and a very good one the next one, while my neighbour might have the opposite problem. All in all I would rather we pool our harvests each year, so that we can have food both years. So we are “trading” part of our harvest for insurance.