The Greek Catenae to the Bible, of which a great number of manuscripts are preserved in numerous libraries of Europe and the East, are of great importance because they furnish the sole tradition for about one-half of all the extant remains of the exegetical writings of the Greek fathers. From them all editions of most of the Greek patristic writers who commented on the Scriptures must draw a large part of their contents. For the textual criticism of the Greek Bible, for the history of Christian thought, and sometimes for the understanding of the biblical writers, they have much to offer. In order, however, that these resources may be used securely, the complete investigation of the whole body of catena-manuscripts is indispensable, and the highly complicated relations of the witnesses to one another make this study peculiarly difficult. Commentaries of all ages are a growth, and in most instances not independent creations. The individual copies of the several catenae almost always differ somewhat, and often very largely, in contents, although they yield unmistakable evidence of relationship in origin; while in details of expression the ancient excerptors and copyists allowed themselves greater freedom than might have been permissible in continuous texts of authors.