Turning then to the Constitution, Marshall asks, "What is commerce?" "Counsel for appellee," he recites, "would limit it to traffic, to buying and selling," to which he answers that "this would restrict a general term ... to one of its significations. Commerce," he continues, "undoubtedly is traffic, but it is something more--it is intercourse," and so includes navigation. And what is the power of Congress over commerce? "It is the power to regulate, that is, the power to prescribe the rule by which commerce is to be governed." It is a power "complete in itself," exercisable "at its utmost extent," and without limitations "other than are prescribed by the Constitution.... If, as has always been understood, the sovereignty of Congress, though limited to specified objects, is plenary as to those objects, the power over commerce with foreign nations and among the several States is vested in Congress as absolutely as it would be in a single government having in its constitution the same restrictions on the exercise of power as are found in the Constitution of the United States." The power, therefore, is not to be confined by state lines but acts upon its subject-matter wherever it is to be found. "It may, of consequence, pass the jurisdictional line of New York and act upon the very waters to which the prohibition now under consideration applies." It is a power to be exercised within the States and not merely at their frontiers. But was it sufficient for Marshall merely to define the power of Congress? Must not the power of the State also be considered? At least, Ogden's attorneys had argued, the mere existence in Congress of the power to regulate commerce among the States did not prevent New York from exercising the same power, through legislation operating upon subject matter within its own boundaries. No doubt, he concedes, the States have the right to enact many kinds of laws which will incidentally affect commerce among the States, such for instance as quarantine and health laws, laws regulating bridges and ferries, and so on; but this they do by virtue of their power of "internal police," not by virtue of a "concurrent" power over commerce, foreign and interstate. And, indeed, New York may have granted Fulton and Livingston their monopoly in exercise of this power, in which case its validity would depend upon its not conflicting with an Act of Congress regulating commerce. For should such conflict exist, the State enactment, though passed "in the exercise of its acknowledged sovereignty," must give place in consequence of the supremacy conferred by the Constitution upon all acts of Congress in pursuance of it, over all state laws whatsoever.