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
It is of course presumed that each species of husbandry was prosecuted under the conditions that suited it, and on the soil which was adapted to its nature. These circumstances were already in themselves sufficient to supersede the husbandry of the petty farmer gradually by the system of farming on a great scale; and it was difficult by means of legislation to counteract them. But an injurious effect was produced by the Claudian law to be mentioned afterwards (shortly before 536), which excluded the senatorial houses from mercantile speculation, and thereby artificially compelled them to invest their enormous capitals mainly in land or, in other words, to replace the old homesteads of the farmers by estates under the management of land- stewards and by pastures for cattle.
Moreover special circumstances tended to favour cattle-husbandry as contrasted with agriculture, although the former was far more injurious to the state. First of all, this form of extracting profit from the soil--the only one which in reality demanded and rewarded operations on a great scale--was alone in keeping with the mass of capital and with the spirit of the capitalists of this age. An estate under cultivation, although not demanding the presence of the master constantly, required his frequent appearance on the spot, while the circumstances did not well admit of his extending the estate or of his multiplying his possessions except within narrow limits; whereas an estate under pasture admitted of unlimited extension, and claimed little of the owner's attention.
For this reason men already began to convert good arable land into pasture even at an economic loss--a practice which was prohibited by legislation (we know not when, perhaps about this period) but hardly with success. The growth of pastoral husbandry was favoured also by the occupation of domain-land. As the portions so occupied were ordinarily large, the system gave rise almost exclusively to great estates; and not only so, but the occupiers of these possessions, which might be resumed by the state at pleasure and were in law always insecure, were afraid to invest any considerable amount in their cultivation--by planting vines for instance, or olives. The consequence was, that these lands were mainly turned to account as pasture.
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