But the force of circumstances caused the Sicilian and Sardinian cultivator to be the most formidable of his immediate competitors. The facility of transport from Sicily to Rome rendered that island superior as a granary to even the more productive portions of the Italian mainland. Sicily could never have revealed the marvellous fertility of the valley of the Po, where a bushel and a half of wheat could be purchased for five pence half-penny, and the same quantity of barley was sold for half this price;[205] but it was easier to get Sicilian corn to Rome by sea than to get Gallic corn to Rome by land; and the system of taxation and requisitions which had grown out of the provincial organisation of the island, rendered it peculiarly easy to place great masses of corn on the Roman market at very short notice. Occasionally the Roman government enforced a sale of corn from the province (_frumentum emptum_),[206] a reasonable price being paid for the grain thus demanded for the city or the army; but this was almost the only case in which the government intervened to regulate supplies. In the ordinary course of things the right to collect the tithes of the province was purchased by public companies, who paid money, not grain, into the Roman treasury, and these companies placed their corn on the market as best they could. The operations of the speculators in grain doubtless disturbed the price at times. But yet the certainty, the abundance and the facilities for transport of this supply were such as practically to shut out from competition in the Roman market all but the most favourably situated districts of Italy. Their chance of competition depended mainly on their accidental possession of a good road, or their neighbourhood to the sea or to a navigable river.[207] The larger proprietors in any part of Italy must have possessed greater facilities for carrying their grain to a good market than were enjoyed by the smaller holders. The Clodian law on trade permitted senators to own sea-going ships of a certain tonnage; they could, therefore, export their own produce without any dependence on the middle-man, while the smaller cultivators would have been obliged to pay freight, or could only have avoided such payment by forming shipping-companies amongst themselves. But such combination was not to be looked for amongst a peasant class, barely conscious even of the external symptoms of the great revolution which was dragging them to ruin, and perhaps almost wholly oblivious of its cause.