The psychologist's final task is to explain the appearance and disappearance, the connections and sequences of these mental objects, the contents of consciousness. But before he can start on explanation of the facts, he has to describe them, and describing means analyzing them into their elements and fixating those elements and their combinations for an exact report. Such descriptive work is in a way preparatory for the further task of real explanation; yet it is in itself important, complicated, and difficult. Of course, it may be easy to separate the complex content into some big groups of facts, to point out that this is a memory idea and this an imaginative idea and the other an abstract idea, and this a perception and that a feeling, this an emotion and that a volition. But such clumsy first discrimination does not go further, perhaps, than does the naturalist's, who tells us that this is a mountain and that a tree, this a pond and that a bird. The real description would demand, of course, an exact measurement of the height of the mountain and the geological analysis of its structure, or an exact classification of the tree and the bird, with a complete description of their organs, and in each organ the various tissues have to be described, and in each tissue the various cells, and the microscopist goes further and describes the structure of the cell. Certainly in the same way the psychologist has to go on to resolve every one of those complex structures; he has to examine the mental tissues and the mental cells of which a volition or a memory idea or a perception are composed. And while he cannot use a microscope for these mental elements, yet his studies may cause elements to appear which the naive observation remains entirely unaware of.