Bearing in mind the statement already made that no federal court can have jurisdiction of any case unless it is one of the classes of cases enumerated in the federal constitution as those to which the judicial power of the federal government may extend, we have to consider briefly the enumeration of these classes of cases found in the federal constitution. In this enumeration (Const. Art. Ill, § 2) we find nine classes of cases, which are considered briefly in the following paragraphs of this chapter.