"Economic theory thus explains why men cooperate through trade. They do so because they are different."

"If all men were equal in interest and endowment, natural or artificial, there would be no organised economic activity to explain. Each man would be a [Robinson] Crusoe. Economic theory thus explains why men cooperate through trade. They do so because they are different."

~ Gordon Tullock, from his (and James Buchanan's) Calculus of Consent