CORRESPONDENCE, a mutual agreement or fitness of parts or character (Lat. cum, with, respondere, to answer; cf. Fr. correspondance). In the 17th and i8th centuries the word was applied to relations and communications between states. It is now chiefly used of the interchange of communications by letter or of the letters themselves. The "doctrine of correspond ence or correspondences," one of the leading tenets of Sweden borgianism, is that every natural object corresponds to and typifies some spiritual principle or truth, this being the only key to the true interpretation of Scripture. In mathematics (q.v.) "correspondence" denotes the relation between members of two groups of objects. (See CURVE.)