The issue of this series has been interrupted by the war. and this volume has been interpolated, for several reasons, somewhat out of its proper place in the order of Bacon's unpublished work, partly out of a consideration of the great importance of the text on which he comments, and partly on account of its influence on his whole work. Mediaeval students will be glad to learn that the publication of the whole of Bacon's work now seems assured.<br><br>As before, I have to acknowledge the ready assistance of mediaeval scholars, among them Prof. A. G. Little, Mr. J. P. Gilson, Dr. Cowley, Dr. Henry Bradley, the Librarian of the Grand-Ducal Library of Saxe-Gotha, who forwarded for study two Arabic MSS. of the Secretum Secretorum, happily returned to him in safety, Mrs. Henry Dakyns, who many years ago copied out and prepared the text of Le Secre de Secrez with a view to joint publication elsewhere, to the Committee of the Bacon Commemoration of 1914, who have materially assisted in the preparation of this volume, and to others named in the Introduction.