But the most important power exercised by the Assembly was its control over taxation in Virginia. In the very first session it made use of this privilege by ordering, "That every man and manservant of above 16 years of age shall pay into the handes and Custody of the Burgesses of every Incorporation and plantation one pound of the best Tobacco".[147] The funds thus raised were utilized for the payment of the officers of the Assembly. The levy by the poll, here used, was continued for many years, and became the chief support of the government. As the colony grew, however, and the need for greater revenues was felt, customs duties and other forms of taxation were resorted to. Large sums were raised by an export duty upon tobacco. At times tariffs were placed upon the importation of liquors, slaves and other articles. But these duties had to be used with great care, for the carrying of the colony was done chiefly by English merchants, and Parliament would permit nothing detrimental to their interests. The Assembly claimed the exclusive right to levy general taxes. The Governor and Council time and again tried to wrest this privilege from them, but never with success.[148] The Burgesses, realizing that their hold upon the exchequer was the chief source of their power, were most careful never to relinquish it. From time to time the Governors sought to evade this restraint by levying taxes under the guise of fees. But this expedient invariably excited intense irritation, and yielded a revenue so small that most Governors thought it best to avoid it entirely. Of more importance were the quit-rents, a tax on land, paid to the King by all freeholders. But this was frequently avoided, and, except at rare intervals, the funds raised by it were left in Virginia to be expended for local purposes. The greatest blow to the power of the Burgesses was struck by the King in 1680, when he forced through the Assembly a law granting to the government a perpetual income from the export duty on tobacco. This revenue, although not large, was usually sufficient to pay the Governor's salary, and thus to render him less dependent upon the Assembly. Finally, it must not be forgotten that the English government, although it refrained from taxing the colony directly, imposed an enormous indirect tax by means of a tariff upon tobacco brought into England. These duties were collected in England, but there can be no doubt that the incidence of the tax rested partly upon the Virginia planters. Despite these various duties, all levied without its consent, the Assembly exercised a very real control over taxation in Virginia, and used it as an effective weapon against the encroachments of the Governors.