In my borrowed copy of Albert O. Hirschman's The Passions and the Interests - which I've only read a third of but recommend unreservedly - a previous reader has pencilled helpful comments in the margin.
This is the bit on Montesquieu, and Hirschman quotes Montesquieu as saying that "the natural effect of commerce is to lead to peace."
The marginalia writer's gloss: natural but unintended
Hirschman: But Montesquieu's praise for commerce is not entirely without reservations - Montesquieu worries about the monetisation of human relations and the loss of hospitality and other moral virtues.
Gloss: the unintended consequence of the CONSEQUENCE
Heh.