The novelty of the Gracchan system lay, not in the manner of taxation, but in the method adopted for securing the returns. The greatest obstacle to the tithe system is the difficulty of instituting an efficient method of collection. To gather in taxes which are paid in kind and to dispose of them to the best advantage, is a heavy burden for a municipality. The desire for a system of contract is sure to arise, and in an Empire the efficient contractor is more likely to be found in the central state than in any of its dependencies. It was of this feeling that Gracchus took advantage when he enacted that the taxes of Asia should be put up for auction at Rome,[638] and that the whole province should be regarded as a single area of taxation at the great auction which the censor held in the capital. It was certain that no foreign competition could prevail in this sale of a kingdom's revenues. The right to gather in the tithes could be purchased only by a powerful company of Roman capitalists. The Decumani of Asia would represent the heart and brain of the mercantile body; they would form a senate and a Principate amongst the Publicani.[639] They would flood the province with their local directors, their agents and their freedmen; and each station would become a centre for a banking business which would involve individuals and cities in a debt, of which the tithe was but a fraction. Nor need their operations be confined to the dominions of Rome; they would spread over Phrygia, rendered helpless by the gift of freedom, and creep into the realms of the neighbouring protected kings, safe in the knowledge that the magic name of "citizen of Rome" was a cover to the most doubtful transaction and a safeguard against the slightest punishment. The collectors were liable to no penalties for extortion, for that crime could be committed only by a Roman magistrate: and their possession of the courts enabled them to raise the spectre of conviction on this very charge before the eyes of any governor who might attempt to check the devastating march of the battalions of commerce.