As soon as we wish to begin to think, we have before us a whole and distinct object--that is, an aggregate of details connected amongst themselves, and separated from their surroundings. Whatever the object, tree, animal, sentiment, event, it is always the same; it always has parts, and these parts always form a whole: this group, more or less vast, comprises others, and is comprised in others, so that the smallest portion of the universe is, like the entire universe, a group. Thus the whole employment of human thought is to reproduce groups. According as a mind is fit for this or not, it is capable or incapable. According as it can reproduce great or small groups, it is great or small. According as it can produce complete groups, or only some of their parts, it is complete or partial. What is it, then, to reproduce a group? It is first to separate therefrom all the parts, then to arrange them in ranks according to their resemblances, then to form these ranks into families, lastly to combine the whole under some general and dominant mark; in short, to imitate the hierarchical classifications of science. But the task is not ended there: this hierarchy is not an artificial and external arrangement, but a natural and internal necessity. Things are not dead, but living; there is in them a force which produces and organizes this group, which binds together the details and the whole, which repeats the type in all its parts. It is this force which the mind must reproduce in itself, with all its effects; it must perceive it by rebound and sympathy: this force must engender in the mind the entire group, and must be developed within it as without it: the series of internal ideas must imitate the series of external; the emotion must follow the conception, vision must complete analysis; the mind must become, like nature, creative. Then only can we say: We know.