105. The inferior courts, established by Congress, have such jurisdiction as Congress in its wisdom sees fit to give them save that the jurisdiction belonging to the Supreme Court cannot be given to an inferior court; there can be but one Supreme Court. The relation of the State courts to the courts of the United States is partly determined by the Constitution, partly by act of Congress. The circumstances under which a case in or from a State court may be transferred, or appealed, to a federal court are various, but the essential reason for such transfer is that the jurisdiction of the United States as defined by the Constitution, a treaty, or an act of Congress, is involved. A case or controversy not involving that jurisdiction cannot arise in any federal court. The possible relations of the Constitution, treaties, and acts of Congress to individuals (persons natural), to corporations (persons artificial, as private corporations), and to States (public corporations), are beyond calculation. The line of demarcation between the jurisdiction of State courts and that of federal courts cannot be fixed by any brief definition or survey. In some instances the jurisdiction is a matter of choice by parties, the court that first takes jurisdiction having it, as it were, by first instance, but in such cases there exists by law a concurrent jurisdiction, judicial procedure being open to parties in either the State or the federal court. In practice, a court restricts itself to its own jurisdiction. 106. It has been said that one test of demarcation between the two jurisdictions is the common law; that each State has the common law but the United States has statute law only. This difference (if true) would restrict federal courts to an exercise of judicial power delegated by the Constitution and set forth in laws made by its authority, while the State courts would administer justice in accord with the law of the States which are both common law and statutory. It must be remembered, however, that federal courts sit in the several States and administer whatsoever law is the local (State) law, taking judicial notice of State statutes, of decisions of State courts, of usages, of the common law as existing in the State, and, therefore, exercising a jurisdiction essentially the same as the State courts. Emphasis may well be placed on the custom of federal courts to follow closely the decisions of State courts,—the result being that State decisions become final in federal courts as do federal decisions in State courts. But the States cannot increase or diminish the jurisdiction of federal courts, nor can Congress increase or diminish the jurisdiction of State courts. Although both courts may have jurisdiction in certain cases, collisions of authority are prevented by good sense and comity among State and federal judges.