 Before presenting the seven parts of the Opus maius, it is important to note a factor that is absent from the scholarship, that is, how Bacon’s Islamic sources structure this major work. These sources, of course, are integrated with his Greek and Latin sources. Most important here for the architecture of the latter work is the De scientiis of Alfarabi. The division of the sciences and the reduction of the linguistic and natural sciences to moral philosophy is strongly influenced by this text. Part four and the latter section of Part six on prognostication, and Part seven, IV, is influenced by Abu Ma’shar’s Introduction to Astronomy and by his Book of Conjunctions. Part five on Perspectiva is a masterpiece of synthesis of most of the major Greek and Muslim texts on Optics. Especially important are the texts of Ptolemy, Alkindi, and Ibn al-Haytham. This synthesis clearly influences Bacon’s new understanding of an experimental science. And yet in addition to this, one must note that Ptolemy in his Almagest, Optics and Astrology influences Bacon’s understanding of method in the sciences as it impacts the integration of reason and experience. And in the third part of the Scientia experimentalis,Bacon is influenced on the important commentary on Ptolemy’Astrology, namely, the Centiloquium by Abu Ja’far IbnYusuf Ibn Ibrahim. But since Bacon’s De multiplication specierum is acknowledged by him as the key to his Optics, one must note the structural presence of the De Radiis attributed to Al-Kindi. This work provides the basis for his doctrine of species that will be spelled out for the geometry of vision in the Perspectiva. Since the Opus maius and related later works are intended as sketch for a grand linguistic, scientific, philosophical and theological work, one must note the important openness that Bacon has for the science, philosophy and theology received from the Muslim and Jewish worlds. This is very different from the Anti-Arabism and the intermittent Anti-Judaism that would become a central part of Western Renaissance culture after 1300.