Speech, that great auxiliary in the interchange of human thought, is no unmixed benefit. It brings to the consciousness of most men incomparably more obscurity than brightness. It enriches their memory with auditory images, not with well-defined pictures of reality. A word, whether written or spoken, excites a sense (sight or hearing), and sets up an activity in the brain. True; it always arouses presentation. A series of musical tones does the same. At an unknown word, at ‘Abracadabra,’ at a proper name, at a tune scraped on the fiddle, we also think of something, but it is either indefinite, or nonsensical, or arbitrary. It is absolute waste of labour to attempt to give a man new ideas, or to widen the circle of his positive knowledge, by means of a word. It can never do more than awaken such ideas as he already possesses. Ultimately everyone works only with the material for presentation which he has acquired by attentive personal observation of the phenomena of the universe. Nevertheless, he cannot do without the stimulus conveyed to him by speech. The desire for knowledge, without any hiatus, of all that is in the world, is irresistible; while the opportunities of perception at first hand, even in the most favourable circumstances, are limited. What we have not ourselves experienced we let others, the dead and the living, tell us. The word must take the place of the direct impressions of sense for us. And then it is itself an impression of sense, and our consciousness is accustomed to put this impression on a level with others, to estimate the idea aroused by this word equally with those ideas which have been acquired through the simultaneous co-operation of all the senses, through observations, and handling on every side, through moving and lifting, listening to, and smelling the object itself. This parity of values is an error of thought. It is false in any case if a word do more than call into consciousness a memory-image of a presentation, which it has acquired through personal experience, or a concept composed of such presentations. Nevertheless, we all of us commit this fallacy. We forget that language was only developed by the race as a means of communication between individuals, that it is a social function, but not a source of knowledge. Words are in reality much more a source of error. For a man can only actually know what he has directly experienced and attentively observed, not what he has merely heard or read, and what he repeats; and if he would free himself from the errors which words have led him into, he has no other means than the increase of his sterling representative material, through personal experience and attentive observation. And since man is never in a position to do this save within certain limits, everyone is condemned to carry on the operations of his consciousness with direct presentations, and at the same time with words. The intellectual structure which is built up with