Murray Rothbard on voluntary exchange

If anyone wishes to grasp how much we owe to the processes of exchange, let him consider what would happen in the modern world if every man were suddenly prohibited from exchanging anything with anyone else.  Eash person would be forced to produce all of his own goods and services himself.  The utter chaos, the total starvation of the great bulk of the human race, and the reversion to primitive subsistence by the remaining handful of people, can readily be imagined.

~ Murray Rothbard, The Ethics of Liberty, p. 35