The Romans have never been noted for jealousy over commerce. It was as a rival nation and not as a trading nation that they attacked Carthage. They favored the cities that engaged in commerce although they were not subjects : thus they increased the might of Marseille by ceding several areas. They feared everything from the barbarians, and nothing from a trading people. Besides, their genius, their glory, their military education, and the form of their government indisposed them for commerce.
In the city, the only concern was wars, elections, intrigues, and trials ; in the countryside, only agriculture ; and in the provinces, a harsh and tyrannical government was incompatible with commerce.
If their political constitution was opposed to it, their law of nations was no less hostile. “The peoples with whom we have neither friendship, nor hospitality, nor alliance,” says the jurisconsult Pomponius, “are not our enemies ; yet if something which belongs to us falls into their hands, they own it ; free men become their slaves ; and they are on the same terms with respect to us.” 
Their civil law was no less oppressive. The law of Constantine, after declaring the children of mean rank who have married persons of high station to be bastards, conflates women who sell things in a shop with slaves, wives of tavern-keepers, women of the theatre, and daughters of a man who runs a house of prostitution or who has been sentenced to combat in the arena  : this came down from the Romans’ ancient institutions.
I quite realize that people full of these two thoughts, one, that commerce is the single most useful thing in the world for a state, and the other that the Romans had the best public order in the world, have believed that they had much encouraged and honored commerce ; but the truth is that they rarely thought about it.