No excuse is needed for presenting to the English reader a History of MediÆval Jewish Philosophy. The English language, poor enough in books on Jewish history and literature, can boast of scarcely anything at all in the domain of Jewish Philosophy. The Jewish Encyclopedia has no article on Jewish Philosophy, and neither has the eleventh edition of the Encyclopedia Britannica. Hastings' Encyclopedia of Religion and Ethics will have a brief article on the subject from the conscientious and able pen of Dr. Henry Malter, but of books there is none. But while this is due to several causes, chief among them perhaps being that English speaking people in general and Americans in particular are more interested in positive facts than in tentative speculations, in concrete researches than in abstract theorizing—there are ample signs that here too a change is coming, and in many spheres we are called upon to examine our foundations with a view to making our superstructure deep and secure as well as broad and comprehensive. And this is nothing else than philosophy. Philosophical studies are happily on the increase in this country and more than one branch of literary endeavor is beginning to feel its influence. And with the increase of books and researches in the history of the Jews is coming an awakening to the fact that the philosophical and rationalistic movement among the Jews in the middle ages is well worth study, influential as it was in forming Judaism as a religion and as a theological and ethical system.

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.

There is not much room for originality in a historical and expository work of this kind, particularly as I believe in writing history objectively. I have not attempted to read into the mediÆval thinkers modern ideas that were foreign to them. I endeavored to interpret their ideas from their own point of view as determined by their history and environment and the literary sources, religious and philosophical, under the influence of which they came. I based my book on a study of the original sources where they were available—and this applies to all the authors treated with the exception of the two Karaites, Joseph al Basir and Jeshua ben Judah, where I had to content myself with secondary sources and a few fragments of the original texts. For the rest I tried to tell my story as simply as I knew how, and I hope the reader will accept the book in the spirit in which it is offered—as an objective and not too critical exposition of Jewish rationalistic thought in the middle ages.

My task would not be done were I not to express my obligations to the Publication Committee of the Jewish Publication Society of America to whose encouragement I owe the impulse but for which the book would not have been written, and whose material assistance enabled the publishers to bring out a book typographically so attractive.