… is from page 412 of the Book III, Chapter iv, of the 1981 Liberty Fund edition of Adam Smith’s 1776 masterpiece, An Inquiry Into the Nature and Causes of the Wealth of Nations:
[C]ommerce and manufactures gradually introduced order and good government, and with them, the liberty and security of individuals, among the inhabitants of the country, who had before lived almost in a continual state of war with their neighbours and of servile dependency upon their superiors. This, though it has been the least observed, is by far the most important of all their effects.