Please note that Mommsen uses the AUC chronology (Ab Urbe Condita), i.e. from the founding of the City of Rome. You can use this reference table to have the B.C. dates
From: The History of Rome, by Theodor Mommsen
Translated with the sanction of the author by William Purdie Dickson
Sterility of the Capitalist Question
A further consequence of the one-sided power of capital was the disproportionate prominence of those branches of business which were the most sterile and the least productive for the national economy as a whole. Industry, which ought to have held the highest place, in fact occupied the lowest. Commerce flourished; but it was universally passive, importing, but not exporting. Not even on the northern frontier do the Romans seem to have been able to give merchandise in exchange for the slaves, who were brought in numbers from the Celtic and probably even from the Germanic territories to Ariminum and the other markets of northern Italy; at least as early as 523 the export of silver money to the Celtic territory was prohibited by the Roman government.
In the intercourse with Greece, Syria, Egypt, Cyrene, and Carthage, the balance of trade was necessarily unfavourable to Italy. Rome began to become the capital of the Mediterranean states, and Italy to become the suburbs of Rome; the Romans had no wish to be anything more, and in their opulent indifference contented themselves with a passive commerce, such as every city which is nothing more than a capital necessarily carries on--they possessed, forsooth, money enough to pay for everything which they needed or did not need. On the other hand the most unproductive of all sorts of business, the traffic in money and the farming of the revenue, formed the true mainstay and stronghold of the Roman economy. And, lastly, whatever elements that economy had contained for the production of a wealthy middle class, and of a lower one making enough for its subsistence, were extinguished by the unhappy system of employing slaves, or, at the best, contributed to the multiplication of the troublesome order of freedmen.
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Reference address : https://www.ellopos.net/elpenor/rome/3-12-management-land-capital.asp?pg=41