The Wealth of Nations by Part 4 Chapter 7 Page 157

one particular market only so great a part of the industry and commerce of Great Britain, it has rendered the whole state of that industry and commerce more precarious and less secure than if their produce had been accommodated to a greater variety of markets.

We must carefully distinguish between the effects of the colony trade and those of the monopoly of that trade. The former are always and necessarily beneficial; the latter always and necessarily hurtful. But the former are so beneficial that the colony trade, though subject to a monopoly, and notwithstanding the hurtful effects of that monopoly, is still upon the whole beneficial, and greatly beneficial; though a good deal less so than it otherwise would be.

The effect of the colony trade in its natural and free state is to open a