But when we come to social or political habits (what we call institutions), we meet with new conditions which produce an inevitable illusion. The members of the same social or political group do not merely habitually perform similar actions; they influence each other by reciprocal actions, they command, coerce, pay each other. Habits here take the form of relations between the different members; when they are of old standing, formulated in official rules, imposed by a visible authority, maintained by a special set of persons, they occupy so important a place in life, that, to the persons under their influence, they appear as external realities. The men, too, who specialise in an occupation or a function which becomes the dominating habit of their lives, appear as grouped in distinct categories (classes, corporations, churches, governments); and these categories are taken for real existences, or at least for organs of various functions in a real existence, namely, society. We follow the analogy of an animal's body so far as to describe the "structure" and the "functions" of a society, even its "anatomy" and "physiology." These are pure metaphors. By the structure of a society we mean the rules and the customs by which occupations and enjoyments are distributed among its members; by its functions we mean the habitual actions by which each man enters into relations with the others. It may be convenient to use these terms, but it should be remembered that the underlying reality is composed entirely of habits and customs.
The study of institutions, however, obliges us to ask special questions about persons and their functions. In respect of social and economic institutions we have to ask what was the principle of the division of labour and of the division into classes, what were the professions and classes, how were they recruited, what were the relations between the members of the different professions and classes. In respect of political institutions, which are sanctioned by obligatory rules and a visible authority, two new series of questions arise. (1) Who were the persons invested with authority? When authority is divided we have to study the division of functions, to analyse the personnel of government into its different groups (supreme and subordinate, central and local), and to distinguish each of the special bodies. In respect of each class of men concerned in the government we shall ask: How were they recruited? What was their official authority? What were their real powers? (2) What were the official rules? What was their form (custom, orders, law, precedent)? What was their content (rules of law)? What was the mode of application (procedure)? And, above all, how did the rules differ from the practice (abuse of power, exploitation, conflicts between executive agents, non-observance of rules)?
After the determination of all the facts which constitute a society, it remains to find the place which this society occupies among the total number of the societies contemporary with it. Here we enter upon the study of international institutions, intellectual, economic, and political (diplomacy and the usages of war); the same questions apply as in the study of political institutions. A study should also be made of the habits common to several societies, and of those relations which do not assume an official form. This is one of the least advanced parts of historical construction.
IV. The outcome of all this labour is a tabulated view of human life at a given moment; it gives us the knowledge of a state of society (in German, Zustand). But history is not limited to the study of simultaneous facts, taken in a state of rest, to what we may call the statics of society. It also studies the states of society at different moments, and discovers the differences between these states. The habits of men and the material conditions under which they live change from epoch to epoch; even when they appear to be constant they do not remain unaltered in every respect. There is therefore occasion to investigate these changes; thus arises the study of successive facts.
Of these changes the most interesting for the work of historical construction are those which tend in a common direction,[194] so that in virtue of a series of gradual differentiations a usage or a state of society is transformed into a different usage or state, or, to speak without metaphor, cases where the men of a given period practise a habit very different from that of their predecessors without any abrupt change having taken place. This is evolution.
Evolution occurs in all human habits. In order to investigate it, therefore, it is enough to turn once more to the series of questions which we used in constructing a tabulated view of society. In respect of each of the facts, conditions, usages, persons invested with authority, official rules, the question is to be asked: What was the evolution of this fact?
This study will involve several operations: (1) the determination of the fact whose evolution is to be studied; (2) the fixing of the duration of the time during which the evolution took place (the period should be so chosen that while the transformation is obvious, there yet remains a connecting link between the initial and the final condition); (3) the establishing of the different stages of the evolution; (4) the investigation of the means by which it was brought about.
V. A series, even a complete series, of all the states of all societies and of all their evolutions would not be enough to exhaust the subject-matter of history. There remains a number of unique facts which we cannot pass over, because they explain the origin of certain states of society, and form the starting-points of evolutions. How could we study the institutions or the evolution of France if we ignored the conquest of Gaul by Cæsar and the invasion of the Barbarians?
This necessity of studying unique facts has caused it to be said that history cannot be a science, for every science has for its object that which is general. History is here in the same situation as cosmography, geology, the science of animal species: it is not the abstract knowledge of the general relations between facts, it is a study which aims at explaining reality. Now, reality exists but once. There has been but a single evolution of the world, of animal life, of humanity. In each of these evolutions the successive facts have not been the product of abstract laws, but of the concurrence, at each moment, of several circumstances of different nature. This concurrence, sometimes called chance, has produced a series of accidents which have determined the particular course taken by evolution.[195] Evolution can only be understood by the study of these accidents; history is here on the same footing as geology or palæontology.
Thus scientific history may go back to the accidents, or events, which traditional history collected for literary reasons, because they struck the imagination, and employ them for the study of evolution. We may thus look for the facts which have influenced the evolution of each one of the habits of humanity. Each event will be arranged under its date in the evolution which it is supposed to have influenced. It will then suffice to bring together the events of every kind, and to arrange them in chronological and geographical order, to have a representation of historical evolution as a whole.