As centralization advanced with the acceleration of human movement, force expressed itself more and more exclusively through money, and the channel in which money chose to flow was in investments in land. The social system fostered the growth of large estates. The Romans always had an inordinate respect for the landed magnate, and a contempt for the tradesman. Industry was reputed a servile occupation, and, under the Republic, the citizen who performed manual labour was almost deprived of political rights. Even commerce was thought so unworthy of the aristocracy that it was forbidden to senators. “The soil was always, in this Roman society, the principal source and, above all, the only measure of wealth.” A law of Tiberius obliged capitalists to invest two-thirds of their property in land. Trajan not only exacted of aspirants to office that they should be rich, but that they should place at least one-third of their fortune in Italian real estate; and, down to the end of the Empire, the senatorial class “was at the same time the class of great landed proprietors.”[30] The more property consolidated, the more resistless the momentum of capital became. Under the Empire small properties grew steadily rarer, and the fewer they were, the greater the disadvantage at which their owners stood. The small farmer could hardly sustain himself in competition with the great landlord. The grand domain of the capitalist was not only provided with a full complement of labourers, vine-dressers, and shepherds, but with the necessary artisans. The poor farmer depended on his rich neighbour even for his tools. “He was what a workman would be to-day who, amidst great factories, worked alone.”[31] He bought dearer and sold cheaper, his margin of profit steadily shrunk; at last he was reduced to a bare subsistence in good years, and the first bad harvest left him bankrupt. The Roman husbandman and soldier was doomed, for nature had turned against him; the task of history is but to ascertain his fate, and trace the fortunes of his country after he had gone. Of the evicted, many certainly drifted to the cities and lived upon charity, forming the proletariat, a class alike despised and lost to self-respect: some were sold into slavery, others starved; but when all deductions have been made, a surplus is left to be accounted for, and there is reason to suppose that these stayed on their farms as tenants to the purchasers. In the first century such tenancies were common. The lessee remained a freeman, under no subjection to his landlord, provided he paid his rent; but in case of default the law was rigorous. Everything upon the land was liable as a pledge, and the tenant himself was held in pawn unless he could give security for what he owed. In case, therefore, of prolonged agricultural depression, all that was left of the ancient rural population could hardly fail to pass into the condition of serfs, bound to the land by debts beyond the possibility of payment.