… is from page 18 of Mark Kishlansky’s engaging 1996 book, A Monarchy Transformed: Britain 1603-1714 :
The vitatlity of growing market-places [in 17th-century Britain] for agricultural surplus meant that local communities were no longer compelled to diversify their output. They could specialize in what best suited their estates and purchase the rest. Speciality cropping, especially of luxuries like wheat, whose low yield made it expensive for the farmhouse table, was one result of the new market-oriented agriculture.
Two quick notes. First, don’t be misled by Kishlansky’s wording to suppose that markets arose only, or even chiefly, as a means for producers to get rid of their “surplus.” It’s rather more that newly specialized producers, sensing opportunities to sell more, produced “surplus” for sale. These “surpluses” were much like the “surpluses” of, say, laundry detergent that Procter & Gamble seeks to sell.
Second, note the role of comparative advantage in guiding agricultural specialization and in raising living standards – a role played here by changing the pattern of internal specialization and trade. Comparative advantage as an explanatory factor for observed patterns of specialization and trade is no more limited to international specialization and trade than is, say, transportation cost.