ment by which purification is perfected is not made uncertain in its usefulness, by its being in the hands of one of our own party, or of a foreigner, if it possesses the attributes of truth. By these latter we mean those Ancients who investigated these things before the advent of Islam.
Now, such is the case. All that is wanted in an enquiry into philosophical reasoning has already been perfectly examined by the Ancients. All that is required of us is that we should go back to their books and see what they have said in this connection. If all that they say be true, we should accept it and if there be something wrong; we should be warned by it. Thus, when we have finished this kind of research we shall have acquired instruments by which we can observe the universe, and consider its general character. For so long as one does not know its general character one cannot know the cheated, and so long as he does net know the created, he can
