The general tendency to believe in the marvellous has filled with miraculous facts the documents of nearly every people. Historically the existence of the devil is much better proved than that of Pisistratus: there has not been preserved a single word of a contemporary of Pisistratus saying that he has seen him; thousands of "ocular witnesses" declare they have seen the devil; few historical facts have been established by so great a number of independent testimonies. However, we do not hesitate to reject the devil and to accept Pisistratus. For the existence of the devil would be irreconcilable with the laws of all the established sciences. For the historian the solution of the problem is obvious.[177] The observations whose results are contained in historical documents are never of equal value with those of contemporary scientists; we have already shown why. The indirect method of history is always inferior to the direct methods of the sciences of observation. If its results do not harmonise with theirs, it is history which must give way; historical science, with its imperfect means of information, cannot claim to check, contradict, or correct the results of other sciences, but must rather use their results to correct its own. The progress of the direct sciences sometimes modifies the results of historical interpretation; a fact established by direct observation aids in the comprehension and criticism of documents. Cases of stigmata and nervous anæsthesia which have been scientifically observed have led to the admission as true of historical narratives of analogous facts, as in the case of the stigmata of certain saints and the possessed nuns of Loudun. But history cannot aid the progress of the direct sciences. It is kept at a distance from reality by its indirect means of information, and must accept the laws that are established by those sciences which come into immediate contact with reality. In order to reject one of these laws new direct observations are necessary. Such revolutions are possible, but they must be brought about from within. History has no power to take the initiative in them. The solution is not so clear in the case of facts which do not harmonise with a body of historical knowledge or with the sciences, still in the embryonic stage, which deal with man. It depends on the opinion we form as to the value of such knowledge. We can at least lay down the practical rule that in order to contradict history, psychology, or sociology, we must have very strong documents, and this is a case which hardly ever occurs. BOOK III _SYNTHETIC OPERATIONS_ CHAPTER I GENERAL CONDITIONS OF HISTORICAL CONSTRUCTION The criticism of documents only yields isolated facts. In order to organise them into a body of science it is necessary to perform a series of synthetic operations. The study of these processes of historical construction forms the second half of Methodology.