There was a continual tension between the central government and its agents: the tax-farmers had to be given enough power to allow them to do their job but not so much that they became strong enough to defy government regulations, to increase the rate of taxation, and to hold back a significant proportion of the rural surplus for their own use. This tension could be contained when the central and provincial governments were strong, but once they began to weaken this rapidly had a cumulative effect. Tax-farmers would keep back more and more of that they owed to the Treasury, using the money to augment their own power. Meanwhile, the government, deprived of the funds it needed to maintain its own forces, grew steadily weaker.