The commerce clause does not, therefore, without more ado, settle the question of what power is left to the States to adopt legislation regulating foreign or interstate commerce in greater or less measure. To be sure, in cases of flat conflict between an act or acts of Congress regulative of such commerce and a State legislative act or acts, from whatever State power ensuing, the act of Congress is today recognized, and was recognized by Marshall, as enjoying an unquestionable supremacy.[526] But suppose, _first_, that Congress has passed no act; or _secondly_, that its legislation does not clearly cover the ground which certain State legislation before the Court attempts to cover--what rules then apply? Since Gibbons _v._ Ogden both of these situations have confronted the Court, especially as regards interstate commerce, hundreds of times, and in meeting them the Court has, first and last, coined or given currency to numerous formulas, some of which still guide, even when they do not govern, its judgment. DOCTRINAL BACKGROUND; WEBSTER'S CONTRIBUTION The earliest, and the most successful, attempt to set forth a principle capable of guiding the Court in adjusting the powers of the States to unexercised power of Congress under the commerce clause was that which was made by Daniel Webster in his argument in Gibbons _v._ Ogden, in the following words: "He contended, * * *, that the people intended, in establishing the Constitution, to transfer from the several States to a general government, those high and important powers over commerce, which, in their exercise, were to maintain a uniform and general system. From the very nature of the case, these powers must be exclusive; that is, the higher branches of commercial regulation must be exclusively committed to a single hand. What is it that is to be regulated? Not the commerce of the several States, respectively, but the commerce of the United States. Henceforth, the commerce of the States was to be a unit; and the system by which it was to exist and be governed, must necessarily be complete, entire and uniform." At the same time Webster conceded "that the words used in the Constitution, 'to regulate commerce,' are so very general and extensive, that they might be construed to cover a vast field of legislation, part of which has always been occupied by State laws; and therefore, the words must have a reasonable construction, and the power should be considered as exclusively vested in Congress, so far, and so far only, as the nature of the power requires."[527]