Étienne Bonnot de Condillac

We have seen how wealth spreads everywhere when trade enjoys full and permanent freedom. It pours continuously from one province into another. Agriculture is flourishing: people cultivate the arts even in the hamlets: each citizen finds a comfortable existence in work of his choice: all is brought to value; and one does not catch a glimpse of those fortunes out of all proportion which bring luxury and wretchedness.
Everything changes in step with different causes which bring blows to freedom of trade. We have run through these causes, which are wars, tolls, customs, guilds, exclusive privileges, taxes on consumption, variations in coinage, exploitation of mines, every kind of government borrowing, the grain police, the luxury of a great capital, the rivalry of nations, finally the spirit of finance which enters every part of the administration.
Then disorder is at its height. Wretchedness grows with luxury: the towns fill with beggars: the countryside loses population; and the state which has contracted huge debts appears to have no further expedients except those which bring about its ruin.

From the concluding chapter to Commerce and Government considered in their mutual relationship, by the Abbé de Condillac of the Académie Française & Member of the Royal Society of Agriculture of Orléans (1776).