The study of Isidore falls roughly into three periods, mediaeval, when the text was used principally for catenae and florilegia, sixteenth-and-seventeenth-century, when it was published and a rudimentary historical account of Isidore worked out from it and from the better-known testimonia, and modern. Of the modern period the outstanding works have been H. Niemeyer's account of Isidore's life and writings, Capo's, Turner's and Lake's studies establishing the relationships of the major western MSS, and the recent work of Dom Andreas Schmid, Die Christologie Isidors von Pelusium, which, by its account of the history of the text, marks a new period in the study. Besides these works, the past fifty years have seen considerable collection of parallels between Isidore's letters and passages in classical or early Christian authors, as well as several detailed discussions of the content of the letters. These discussions have uniformly been undistinguished expositions of the obvious, and the largest collection of parallels, that of L. Bayer, merited the crushing review it was given by K. Fuhr and has since been considerably supplemented by articles which individually, however, are minor.