If, by such a system of administration, smuggling to any considerable extent could be prevented, even under pretty high duties; and if every duty was occasionally either heightened or lowered according as it was most likely, either the one way or the other, to afford the greatest revenue to the state; taxation being always employed as an instrument of revenue, and never of monopoly; it seems not improbable that a revenue, at least equal to the present neat revenue of the customs, might be drawn from duties upon the importation of only a few sorts of goods of the most general use and consumption; and that the duties of customs might thus be brought to the same degree of simplicity, certainty, and precision, as those of excise.