The Wealth of Nations by Part 2 Chapter 5 Page 6

multiplied so as to hurt the public, though they may so as to hurt one another. The quantity of grocery goods, for example, which can be sold in a particular town is limited by the demand of that town and its neighbourhood. The capital, therefore, which can be employed in the grocery trade cannot exceed what is sufficient to purchase that quantity. If this capital is divided between two different grocers, their competition will tend to make both of them sell cheaper than if it were in the hands of one only; and if it were divided among twenty, their competition would be just so much the greater, and the chance of their combining together, in order to raise the price, just so much the less.

Their competition might perhaps ruin some of themselves; but to take care of this is the business of the parties concerned, and it may