"A Kingdom," said Locke, "grows rich or poor just as a farmer does, and no other way"; and while there is a sense in which this is wholly true, the meaning attached to it by the mercantilists was that foreign competition meant national weakness.
They could not conceive a commercial bargain which was profitable to both sides.

Nations grow prosperous at each other's expense; wherefore a woolen trade in Ireland necessarily spells English unemployment.

Even Davenant, who was in many respects on the high road to free trade, was in this problem adamant.

Protection was essential in the colonial market; for unless the trade of the colonies was directed through England they might be dangerous rivals.

So Ireland and America were sacrificed to the fear of British merchants, with the inevitable result that repression brought from both the obvious search for remedy.
Herein it might appear that Adam Smith had novelty to contribute; yet nothing is more certain than that his full sense of the world as the only true unit of marketing was fully grasped before him.