"The Rational Optimist: How Prosperity Evolves, Matt Ridley elaborates: "'If I sew you a hide tunic today, you can sew me one tomorrow' brings limited rewards and diminishing returns. '[But] ... I make the clothes, you catch the food' brings increasing returns. Indeed, it has the beautiful property that it does not even need to be fair. For barter to work, two individuals do not need to offer things of equal value. Trade is often unequal but it still benefits both sides."