But we have traveled a little too fast.  Were the symbol “house”—­whether an auditory, motor, or visual experience or image—­attached but to the single image of a particular house once seen, it might perhaps, by an indulgent criticism, be termed an element of speech, yet it is obvious at the outset that speech so constituted would have little or no value for purposes of communication.  The world of our experiences must be enormously simplified and generalized before it is possible to make a symbolic inventory of all our experiences of things and relations; and this inventory is imperative before we can convey ideas.  The elements of language, the symbols that ticket off experience, must therefore be associated with whole groups, delimited classes, of experience rather than with the single experiences themselves.  Only so is communication possible, for the single experience lodges in an individual consciousness and is, strictly speaking, incommunicable.  To be communicated it needs to be referred to a class which is tacitly accepted by the community as an identity.  Thus, the single impression which I have had of a particular house must be identified with all my other impressions of it.  Further, my generalized memory or my “notion” of this house must be merged with the notions that all other individuals who have seen the house have formed of it.  The particular experience that we started with has now been widened so as to embrace all possible impressions or images that sentient beings have formed or may form of the house in question.  This first simplification of experience is at the bottom of a large number of elements of speech, the so-called proper nouns or names of single individuals or objects.  It is, essentially, the type of simplification which underlies, or forms the crude subject of, history and art.  But we cannot be content with this measure of reduction of the infinity of experience.  We must cut to the bone of things, we must more or less arbitrarily throw whole masses of experience together as similar enough to warrant their being looked upon—­mistakenly, but conveniently—­as identical.  This house and that house and thousands of other phenomena of like character are thought of as having enough in common, in spite of great and obvious differences of detail, to be classed under the same heading.  In other words, the speech element “house” is the symbol, first and foremost, not of a single perception, nor even of the notion of a particular object, but of a “concept,” in other words, of a convenient capsule of thought that embraces thousands of distinct experiences and that is ready to take in thousands more.  If the single significant elements of speech are the symbols of concepts, the actual flow of speech may be interpreted as a record of the setting of these concepts into mutual relations.