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 created, and so long as he does not know the created, he can have no knowledge of the Creator. Thus we must begin an inquiry into the universe systematically, such as we have learned from the trend of rational inference. It is also evident that this aim is to be attained by the investigation of one part of the universe after another, and that help must be derived from predecessors, as is the case in other sciences. Imagine that the science of geometry and astronomy had become extinct in our day, and a single individual desired to find out by himself the magnitude of the heavenly bodies, their forms, and their distances from one another. Even though he were the most sagacious of men, it would be as impossible for him as to ascertain the proportion of the sun and the earth and the magnitude of the other stars. It would only be attainable by aid of divine revelation, or something like it. If it be said to him that the sun is a hundred and fifty or sixty times as big as the earth, he would take it to be sheer madness on the part of the speaker, though it is an established fact in the science of astronomy, so that no one learned in that science will have any doubt about it. The science which needs most examples from other sciences is that of Law. For the study of jurisprudence cannot be completed except in a very long time. If a man today would himself learn of all the arguments discovered by the different disputants of diverse sects, in problems which have always excited contentions in all the big cities, except those of Al-Maghrib, he would be a proper object to be laughed at on account of the impossibility of the task, in spite of the existence of every favourable circumstance. This is similar not only in the sciences but also in the arts. For no one is capable of discovering by himself alone everything which is required. And if this is so in other sciences and arts, how is it possible in the art of arts--philosophy?