One cannot maintain that this kind of reasoning is an innovation in religion because it did not exist in the early days of Islam. For legal reasoning and its kinds are things which were invented also in later ages, and no one thinks they are innovations. Such should also be our attitude towards philosophical reasoning. There is another reason why it should be so, but this is not the proper place to mention it. A large number of the followers of this religion confirm philosophical reasoning, all except a small worthless minority, who argue from religious ordinances. Now, as it is established that the Law makes the consideration of philosophical reasoning and its kinds as necessary as legal reasoning, if none of our predecessors has made an effort to enquire into it, we should begin to do it, and so help them, until the knowledge is complete. For if it is difficult or rather impossible for one person to acquaint himself single-handed with all things which it is necessary to know in legal matters, it is still more difficult in the case of philosophical reasoning. And, if before us, somebody has enquired into it, we should derive help from what he has said. It is quite immaterial whether that man is our co-religionist or not; for the instrument 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.