But it is not merely the English language that is still wanting in a general history of Mediæval Jewish Philosophy, the German, French and Italian languages are no better off in this regard. For while it is true that outside of the Hebrew and Arabic sources, German books and monographs are the _sine qua non_ of the student who wishes to investigate the philosophical movement in mediæval Jewry, and the present writer owes very much to the researches of such men as Joel, Guttmann, Kaufmann and others, it nevertheless remains true that there is as yet no complete history of the subject for the student or the general reader. The German writers have done thorough and distinguished work in expounding individual thinkers and problems, they have gathered a complete and detailed bibliography of Jewish philosophical writings in print and in manuscript, they have edited and translated and annotated the most important philosophical texts. France has also had an important share in these fundamental undertakings, but for some reason neither the one nor the other has so far undertaken to present to the general student and non-technical reader the results of their researches. What was omitted by the German, French and English speaking writers was accomplished by a scholar who wrote in Hebrew. Dr. S. Bernfeld has written in Hebrew under the title "Daat Elohim" (The Knowledge of God) a readable sketch of Jewish Religious philosophy from Biblical times down to "Ahad Haam." A German scholar (now in America), Dr. David Neumark of Cincinnati, has undertaken on a very large scale a History of Jewish Philosophy in the Middle Ages, of which only a beginning has been made in the two volumes so far issued. The present writer at the suggestion of the Publication Committee of the Jewish Publication Society of America has undertaken to write a history of mediæval Jewish rationalistic philosophy in one volume--a history that will appeal alike to the scholar and the intelligent non-technical reader. Treating only of the rationalistic school, I did not include anything that has to do with mysticism or Kabbala. In my attempt to please the scholar and the layman, I fear I shall have succeeded in satisfying neither. The professional student will miss learned notes and quotations of original passages in the language of their authors. The general reader will often be wearied by the scholastic tone of the problems as well as of the manner of the discussion and argument. And yet I cannot but feel that it will do both classes good--the one to get less, the other more than he wants. The latter will find oases in the desert where he can refresh himself and take a rest, and the former will find in the notes and bibliography references to sources and technical articles where more can be had after his own heart.