(3) _Physics._ The object of this science is the study of the bodies which compose the universe: the sky and the stars, and, here below, simple elements such as air, earth, water, fire, and compound bodies—animals, plants, and minerals; the reasons of their changes, developments, and intermixture. By the nature of its researches it is closely connected with the study of medicine, the object of which is the human body, its principal and secondary organs, and the law which governs their changes. Religion having no fault to find with medical science, can not justly do so with physical, except on some special, matters which we have mentioned in the work entitled, "The Destruction of the Philosophers." Besides these primary questions, there are some subordinate ones depending on them, on which physical science is open to objection. But all physical science rests, as we believe, on the following principle: Nature is entirely subject to God; incapable of acting by itself, it is an instrument in the hand of the Creator; sun, moon, stars, and elements are subject to God and can produce nothing of themselves. In a word, nothing in nature can act spontaneously and apart from God. (4) _Metaphysics._ This is the fruitful breeding-ground of the errors of philosophers. Here they can no longer satisfy the laws of rigorous argumentation such as logic demands, and this is what explains the disputes which arise between them in the study of metaphysics. The system most closely akin to the system of the Mohammedan doctors is that of Aristotle as expounded to us by Farabi and Avicenna. The sum total of their errors can be reduced to twenty propositions: three of them are irreligious, and the other seventeen heretical. It was in order to combat their system that we wrote the work, "Destruction of the Philosophers." The three propositions in which they are opposed to all the doctrines of Islam are the following: (_a_) Bodies do not rise again; spirits alone will be rewarded or punished; future punishments will be therefore spiritual and not physical. They are right in admitting spiritual punishments, for there will be such; but they are wrong in rejecting physical punishments, and contradicting in this manner the assertions of the Divine Law. (_b_) "God takes cognizance of universals, not of specials." This is manifestly irreligious. The Koran asserts truly, "Not an atom's weight in heaven or earth can escape his knowledge" (x. 62). (_c_) They maintain that the universe exists from all eternity and will never end. None of these propositions has ever been admitted by Moslems.