While Abraham Ibn Daud is thus expressly unsympathetic to Gabirol and tacitly in disagreement with Halevi (he does not mention him), he shows the closest relation to Maimonides, whose forerunner he is. We feel tempted to say that if not for Ibn Daud there would have been no Maimonides. And yet the irony of history has willed that the fame of being the greatest Jewish philosopher shall be Maimonides's own, while his nearest predecessor, to whose influence he owed most, should be all but completely forgotten. The Arabic original of Ibn Daud's treatise is lost, and the Hebrew translations (there are two) lay buried in manuscript in the European libraries until one of them was published by Simson Weil in 1852.[225] Abraham Ibn Daud is the first Jewish philosopher who shows an intimate knowledge of the works of Aristotle and makes a deliberate effort to harmonize the Aristotelian system with Judaism. To be sure, he too owes his Aristotelian knowledge to the Arabian exponents of the Stagirite, Alfarabi and Avicenna, rather than to the works of Aristotle himself. But this peculiarity was rooted in the intellectual conditions of his time, and must not be charged to his personal neglect of the sources. And Maimonides does nothing more than repeat the effort of Ibn Daud in a more brilliant and masterly fashion. The development of the three religious philosophies in the middle ages, Jewish, Christian and Mohammedan, followed a similar line of progression. In all of them it was not so much a development from within, the unfolding of what was implicit and potential in the original germ of the three respective religions, as a stimulus from without, which then combined, as an integral factor, with the original mass, and the final outcome was a resultant of the two originally disparate elements. We know by this time what these two elements were in each case, Hellenic speculation, and Semitic religion in the shape of sacred and revealed documents. The second factor was in every case complete when the process of fusion began. Not so the first. What I mean is that not all of the writings of Greek antiquity were known to Jew, Christian and Mohammedan at the beginning of their philosophizing career. And the progress in their philosophical development kept equal step with the successive accretion of Greek philosophical literature, in particular Aristotle's physical, psychological and metaphysical treatises, and their gradual purgation of Neo-Platonic adhesions.