At the beginning of the sixth century A.H., a younger contemporary of al-Ghazali, we have _Abu Bakr ibn Bajja_ (d. 533 A.H. = 1138 A.D.), the first of the Muslim philosophers of Spain. By this time, some three-quarters of a century after the death of Ibn Sina, Arabic philosophy was almost extinct in Asia and was treated as a dangerous heresy. In Egypt, it is true, there was a greater degree of toleration, though less than in the golden age of the Fatimids, but Egypt was regarded with suspicion as the home of heresy and of forms of superstition which were uncongenial to the philosopher. Spain thus becomes the place of refuge for Muslim philosophy as it had already become the nursery of Jewish speculation. Ibn Bajja, known to the Latin schoolmen as “Avempace,” found in Murabit Spain the freedom and toleration which Asia no longer afforded. He continues the work of al-Farabi, not, it will be noted, of Ibn Sina, and develops the neo-Platonic interpretation of Aristotle on sober and conservative lines. He wrote commentaries on Aristotle’s Physics, _de generatione et corruptione_, and the _Meteora_; he produced original works on mathematics, on “the soul,” and a treatise which he called “The Hermit’s Guide,” which was used by Ibn Rushd (Averroes) and by the Jewish writer Moses of Narbonne in the 14th cent. A.D. In this last work he makes a distinction between “animal activity,” in which action is due to the prompting of the emotions, passions, etc., and “human activity,” which is suggested and directed by abstract reason, and from this distinction draws a rule of life and conduct. He is chiefly cited by the Latin schoolmen with reference to the doctrine of “separate substances.” “Avempace held that, by the study of the speculative sciences, we are able by means of the images which we know from these ideas to attain to the knowledge of separate substances” (St. Thomas Aq. _c. Gentiles_, 3, 41). This question as to the possibility of knowing substances separated, i.e. abstracted, from the concrete bodies in which they exist in combination--and the “separate substances” were regarded as spiritual things--was prominent in mediæval scholasticism, which inherited it from the Arabic philosophers, and from it came the further question whether the contemplation of such abstract ideas gives us a better knowledge of realities than observation of the concrete bodies. Both Albertus Magnus and St. Thomas Aquinas associate Avempace especially with this question and with the doctrine of the “acquired intellect,” to which we have already referred in our notes on Ibn Sina, and which completes the theory of “separate substances” by supposing that intelligible forms stream into our souls from an outside Agent Intellect by way of emanation as substantial forms descend on corporeal matter. St. Thomas Aquinas shows direct knowledge of Avempace’s treatment of these subjects, but this is not so evident in Albertus.