The sciences of direct observation deal with realities, taken in their entirety. The science which borders most closely on history in respect of its subject-matter, descriptive zoology, proceeds by the examination of a real and complete animal. This animal is first observed, as a whole, by actual vision; it is then dissected into its parts; this dissection is analysis in the original sense of the word (ἁναλὑειν, to break up into parts). It is then possible to put the parts together again in such a way as to exhibit the structure of the whole; this is real synthesis. It is possible to watch the real movements which are the functions of the organs in such a way as to observe the mutual actions and reactions of the different parts of the organism. It is possible to compare real wholes and see what are the parts in which they resemble each other, so as to be able to classify them according to real points of resemblance. The science is a body of objective knowledge founded on real analysis, synthesis, and comparison; actual sight of the things studied guides the scientific researcher and dictates the questions he is to ask himself.
In history there is nothing like this. One is apt to say that history is the "vision" of past events, and that it proceeds by "analysis": these are two metaphors, dangerous if we suffer ourselves to be misled by them.[181] In history we see nothing real except paper with writing on it—and sometimes monuments or the products of art or industry. The historian has nothing before him which he can analyse physically, nothing which he can destroy and reconstruct. "Historical analysis" is no more real than is the vision of historical facts; it is an abstract process, a purely intellectual operation. The analysis of a document consists in a mental search for the items of information it contains, with the object of criticising them one by one. The analysis of a fact consists in the process of distinguishing mentally between its different details (the various episodes of an event, the characteristics of an institution), with the object of paying special attention to each detail in turn; that is what is called examining the different "aspects" of a fact,—another metaphor. The human mind is vague by nature, and spontaneously revives only vague collective impressions; to impart clearness to these it is necessary to ask what individual impressions go to form a given collective impression, in order that precision may be attained by a successive consideration of them. This is an indispensable operation but we must not exaggerate its scope. It is not an objective method which yields a knowledge of real objects; it is only a subjective method which aims at detecting those abstract elements which compose our impressions.[182] From the very nature of its materials history is necessarily a subjective science. It would be illegitimate to extend to this intellectual analysis of subjective impressions the rules which govern the real analysis of real objects.
History, then, must guard against the temptation to imitate the method of the biological sciences. Historical facts are so different from the facts of the other sciences that their study requires a different method.
III. Documents, the sole source of historical knowledge, give information on three categories of facts:
(1) Living beings and material objects. Documents make us acquainted with the existence of human beings, physical conditions, products of art and industry. In all these cases physical facts have been brought before the author by physical perception. But we have before us nothing but intellectual phenomena, facts seen "through the author's imagination," or, to speak accurately, mental images representative of the author's impressions—images which we form on the analogy of the images which were in his mind. The Temple at Jerusalem was a material object which men saw, but we cannot see it now; all we can now do is to form a mental image of it, analogous to that which existed in the minds of those who saw and described it.
(2) Actions of men. Documents relate the actions (and words) of men of former times. Here, too, are physical facts which were known to the authors by sight and hearing, but which are now for us no more than the author's recollections, subjective images which are reproduced in our minds. When Cæsar was stabbed the dagger-thrusts were seen, the words of the murderers were heard; we have nothing but mental images. Actions and words all have this characteristic, that each was the action or the word of an individual; the imagination can only represent to itself individual acts, copied from those which are brought before us by direct physical observation. As these are the actions of men living in a society, most of them are performed simultaneously by several individuals, or are directed to some common end. These are collective acts; but, in the imagination as in direct observation, they always reduce to a sum of individual actions. The "social fact," as recognised by certain sociologists, is a philosophical construction, not an historical fact.
(3) Motives and conceptions. Human actions do not contain their own cause within themselves; they have motives. This vague word denotes both the stimulus which occasions the performance of an action, and the representation of the action which is in the mind of a man at the moment when he performs it. We can imagine motives only as existing in a man's mind, and in the form of vague interior representations, analogous to those which we have of our own inward states; we can express them only by words, generally metaphorical. Here we have psychic facts, generally called feelings and ideas. Documents exhibit three kinds of such facts: (a) motives and conceptions in the authors' minds and expressed by them; (b) motives and ideas attributed by the authors to contemporaries of theirs whose actions they have seen; (c) motives which we ourselves may suppose to have influenced the actions related in the documents, and which we represent to ourselves on the model of our own motives.
Physical facts, human actions (both individual and collective), psychic facts—these form the objects of historical knowledge; they are none of them observed directly, they are all imagined. Historians—nearly all of them unconsciously and under the impression that they are observing realities—are occupied solely with images.
IV. How, then, is it possible to imagine facts without their being wholly imaginary? The facts, as they exist in the historian's mind, are necessarily subjective; that is one of the reasons given for refusing to recognise history as a science. But subjective is not a synonym of unreal. A recollection is only an image; but it is not therefore a chimera, it is the representation of a vanished reality. It is true that the historian who works with documents has no personal recollections of which he can make direct use; but he forms mental images on the model of his own recollections. He assumes that realities (objects, actions, motives), which have now disappeared, but were formerly observed by the authors of the documents, resembled the realities of his own day which he has himself seen and which he retains in his memory. This is the postulate of all the documentary sciences. If former humanity did not resemble the humanity of to-day, documents would be unintelligible. Starting from this assumed resemblance, the historian forms a mental representation of the bygone facts of history similar to his own recollection of the facts he has witnessed.
This operation, which is performed unconsciously, is one of the principal sources of error in history. The things of the past which are to be pictured in imagination were not wholly similar to the things of the present which we have seen; we have never seen a man like Cæsar or Clovis, and we have never experienced the same mental states as they. In the established sciences it is equally true that one man will work on facts which another has observed, and which he must therefore represent to himself by analogy; but these facts are defined by precise terms which indicate what invariable elements ought to appear in the image. Even in physiology the notions which occur are sufficiently clear and fixed for the same word to evoke in the minds of all naturalists similar images of an organ or a movement. The reason is that each notion which has a name has been formed by a method of observation and abstraction in the course of which all the characteristics which belong to the notion have been precisely determined and described.