(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.