Applying the general principle that equity will only take jurisdiction where there is no relief possible at law, it follows that, in general, the fields of the jurisdiction of the equity courts and of the common law courts will be distinct from each other, and that whenever one set of courts have jurisdiction, the other will not.

In some cases, however, we find concurrent jurisdiction of the two courts. Such concurrent jurisdiction may arise in four different ways:

(a) Equity may take jurisdiction on account of the fact that there is no remedy at law, and later a common law remedy may be given.

(b) Equity may take jurisdiction in cases where there is a common law remedy, which is, however, not certain, complete, and adequate.

(c) In cases where jurisdiction is given to equity by statute, over cases where the common law courts already have jurisdiction.

(d) Where an equity court properly acquiies jurisdiction on account of some peculiar equitable principle or remedy involved in the suit, such court may also, in the same case, grant other relief which could have been obtained at common law.

2 16 Cyc, pp. 23-4.

Illustrations of these different classes of cases will be given in the appropriate places in this book.