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. ISAAC HUSIK. PHILADELPHIA, _July, 1916._ TABLE OF CONTENTS PAGE PREFACE vii INTRODUCTION xiii CHAPTER I. ISAAC ISRAELI 1 II. DAVID BEN MERWAN AL MUKAMMAS 17 III. SAADIA BEN JOSEPH AL-FAYYUMI 23 IV. JOSEPH AL-BASIR AND JESHUA BEN JUDAH 48 V. SOLOMON IBN GABIROL 59 VI. BAHYA IBN PAKUDA 80 VII. PSEUDO-BAHYA 106 VIII. ABRAHAM BAR HIYYA 114 IX. JOSEPH IBN ZADDIK 125 X. JUDAH HALEVI 150 XI. MOSES AND ABRAHAM IBN EZRA 184 XII. ABRAHAM IBN DAUD 197 XIII....