We _name_ the isolates; that is, we apply to each an arbitrary symbol to stand for the isolated quality or relation. All words (except the obviously onomatopoetic, such as "bow-wow," "cuckoo," etc.) are arbitrary symbols associated with objects, or qualities, or relations, or other phenomena. And abstract names of isolates are, so to speak, the pegs on which we hang the qualities we have separated by analysis and isolation, while class-names are pegs upon which we can hang a group of similars reached by the process of isolation; for all classing and grouping of objects, or qualities, or relations involves, so far as the process is a conscious one, the principle of analysis. In classing objects, we group them in reference to certain characters which they have in common, disregarding certain other characters in which they differ. We group together, for example, sights, or sounds, or smells, and distinguish them from each other and from tastes and touches. And then we go further, and class all these together as sensations having certain characteristics in common whereby they are distinguished from perceptions of relation and so forth. Perhaps it may be objected that classification comes much earlier in the mental process than I am now putting it. It may be said that the recognition of a sensation as a touch, or a smell, or a sound involves a classification of sensations in these categories, and that the simple perception of an orange involves the placing of the object in this class of bodies. And, undoubtedly, we have here the germs of the process. Sensation and perception give us the materials for classification; the perception of similarity and difference gives us the _sine quâ non_ of the process. Nevertheless, although there may be an earlier unconscious grouping of phenomena, it is only when the mind is specially directed to these materials, with the object of grouping them according to their similarities, that we can speak of classification proper--conscious and intentional classification, as opposed to unconscious grouping. And this involves the intentional selection of the points of similarity, and discarding or neglecting the points of difference. It involves the process of analysis or isolation. There is a vast difference between the perceptual recognition of objects as similar, and conceptual classification on grounds of similarity. Just as the recognition of a sensation as now and not then, or here and not there, or as due to something outside us, gives us the germs from which, on ultimate analysis, our ideas of time, space, and causation are reached; so does the recognition of these sensations as of this kind and not that give us the germ from which, on analysis, the process of classification may arise. True, conscious, scientific classification is late in development.