… is from page 72 of Matt Ridley’s marvelous 2010 book, The Rational Optimist :
The extraordinary thing about exchange is that it breeds: the more of it you do, the more of it you can do. And it calls forth innovation.
Much suspicion of, and hostility to, international trade is akin to atavistic superstitions that raised in some peoples suspicions of, and hostility to, mating with individuals outside of those people’s ethnic or racial or religious groups. “Only We are worthy of your seed or your womb – They are not!” “Corruption of the purity of Our race is the inevitable result of your conjugal mixing with Them!”
Or only slightly differently: protectionism is much like in-breeding. Like in-breeding, protectionism weakens the economy that practices it. Like in-breeding, protectionism causes the group that practices it to become ever-more stupid, uncreative, fragile, and vulnerable – a population of pathetic misfits destined to be weaker and poorer than are their more-cosmopolitan and open neighbors.