But neither they nor their Mohammedan predecessors succeeded in working out a complete system of theology. They left untouched essential elements of religion which do not come within the sphere of rational verities, and did not give proper appreciation to the rich treasures of faith deposited in the Biblical and Rabbinical literature. Nor does the comprehensive theological system of Maimonides, which for centuries largely shaped the intellectual life of the Jew, form an exception. Only the mystics, Bahya at their head, paid attention to the spiritual side of Judaism, dwelling at length on such themes as prayer and repentance, divine forgiveness and holiness. 4. Closer acquaintance with the religious and philosophical systems of modern times has created a new demand for a Jewish theology by which the Jew can comprehend his own religious truths in the light of modern thought, and at the same time defend them against the aggressive attitude of the ruling religious sects. Thus far, however, the attempts made in this direction are but feeble and sporadic; if the structure is not to stand altogether in the air, the necessary material must be brought together from its many sources with painstaking labor.(4) The special difficulty in the task lies in the radical difference which exists between our view of the past and that of the Biblical and medieval writers. All those things which have heretofore been taken as facts because related in the sacred books or other traditional sources, are viewed to-day with critical eyes, and are now regarded as more or less colored by human impression or conditioned by human judgment. In other words, we have learned to distinguish between _subjective_ and _objective_ truths,(5) whereas theology by its very nature deals with truth as absolute. This makes it imperative for us to investigate historically the leading idea or fundamental principle underlying a doctrine, to note the different conceptions formed at various stages, and trace its process of growth. At times, indeed, we may find that the views of one age have rather taken a backward step and fallen below the original standard. The progress need not be uniform, but we must still trace its course.