Smith is known as the founder of economics, but he was so much moıre. Just one of many examples can be found in his discussion of colonialism in Part IV, Chapter VII of An Inquiry into the Nature and Causes of the Wealth of Nations.
Smith distinguishes between Greek colonialism and Roman colonialism, in an analysis that becomes an account of the end of political liberty in antiquity, for reasons tied political economy (which is the sphere of natural liberty if handled correctly).
Smith suggests that Greek colonialism was the transfer of ‘surplus’ population to new political communities which were free from the originating in trade as in political matters. Roma colonialism though was a means of expanding the sovereignty of Rome, by transferring land to the ‘surplus’ population of Rome in areas which were to be incorporated into Roman lands, or where Roman sovereignty would be reinforced by settlers with new land.
The new landholdings of Roman colonies were in Italy during the history of the Roman Republic, and this became the basis of the Social Wars, which were resolved by giving citizenship rights to colonists in Italy. However, this apparent generosity ruined the Roman Republic, so that republicanism came to an end. Republicanism comes to an end because it was participatory in the ancient world, that is relied on citizens gathering together. Once Roman citizenship spreads beyond those resident in the city, then there are too many people who live too far away for participatory republicanism to work. Adding to the problems, gangs of Italians could be introduced into the city for deliberation manipulation of republican politics.
Smith regrets the end of antique republicanism, but does not regret it entirely. He links the power of Emperors with the improved rights of slaves, commenting that slavery is stronger where there is political liberty, since government cannot make citizens treat property in any particular way. Roman Emperors did give slaves protection from abuse.
Political economy problems led the Ancient Roman Republic to find a colonial solution which destroyed republicanism, but allowed some extension of the protection of ‘natural liberty’. So we see a complex interaction between natural liberty, political liberty and political economy in Smith. hHe writes in the hope of situations in which good political economy, natural liberty, and republican liberty can be aligned.