The Wealth of Nations by Part 1 Chapter 10 Page 81

In every country of Europe we find, at least, a hundred people who have acquired great fortunes from small beginnings by trade and manufactures, the industry which properly belongs to towns, for one who has done so by that which properly belongs to the country, the raising of rude produce by the improvement and cultivation of land. Industry, therefore, must be better rewarded, the wages of labour and the profits of stock must evidently be greater in the one situation than in the other. But stock and labour naturally seek the most advantageous employment. They naturally, therefore, resort as much as they can to the town, and desert the country.

The inhabitants of a town, being collected into one place, can easily combine together. The most insignificant trades carried on in towns have accordingly, in some place or other,