In that case, also, they would have been of no use. Who is it, then, who has fitted this to that and that to this? And who is it that has fitted the knife to the case and the case to the knife? Is it no one? And, indeed, from the very structure of things which have attained their completion, we are accustomed to show that the work is certainly the act of some artificer, and that it has not been constructed without a purpose. Does then each of these things demonstrate the workman, and do not visible things and the faculty of seeing and light demonstrate Him?