iv. We are not called upon to believe that anything is really contrary

to, or in violation of, nature St. Augustine laid down, some fifteen centuries ago: ‘Portentum ergo fit non contra naturam sed contra quam est nota natura’ (_De Civitate Dei_, xxi. 8). We can always exercise an act of faith, that if we really knew what had taken place, and if we really knew the highest laws of the universe, there would not be any contradiction between them. As it is, there is a double margin of error: it is difficult, and in many cases impossible, for us so to translate the language of the distant past into the idiom of the present as to be sure that we can realize what are the facts that we have to deal with; and, even if we had got the facts, we should still have but a very imperfect knowledge of the causes by which they were determined.