The most important single central fact about a free market is that no exchange takes place unless both parties benefit.
Milton FriedmanEconomists may not know much. But we know one thing very well: how to produce surpluses and shortages. Do you want a surplus? Have the government legislate a minimum price that is above the price that would otherwise prevail. That is what we have done at one time or another to produce surpluses of wheat, of sugar, of butter, of many other commodities. Do you want a shortage? Have the government legislate a maximum price that is below the price that would otherwise prevail.
Milton Friedman