The importance that attaches to language can hardly be overestimated. When the child acquires the use of language, he has acquired the use of a tool, the importance of which to thinking is greater than that of any other tool. Now, one can think without language, in the sense that memory images come and go,--we have defined thinking as the flow of imagery, the passing or succession of ideas. But after we have named things, thinking, particularly reasoning, becomes largely verbal, or as we said above, _talking to oneself_. Not only do we give names to concrete things but we give names to specific attributes and to relations. As we organize and analyze our experiences, there appear uniformities, principles, laws. To these we give names, such as white, black, red, weight, length, thickness, justice, truth, sin, crime, heat, cold, mortal, immortal, evolution, disintegration, love, hate, envy, jealousy, possible, impossible, probable, etc. We spoke above of meanings. To meanings we give names, so that a single word comes to stand for meanings broad and significant, the result of much experience. Such words as "evolution" and "gravitation," single words though they are, represent a wide range of experiences and bring these experiences together and crystallize them into a single expression, which we use as a unit in our thought. Language, therefore, makes thought easier and its accomplishment greater. After we have studied Cæsar for some years, the name comes to represent the epitome, the bird's-eye view of a great man. A similar thing is true of our study of other men and movements and things. Single words come to represent a multitude of experiences. Then these words become associated and organized in accordance with the principles of association discussed above, so that it comes about that the older we are, the more we come to think in words, and the more these words represent. The older we are, the more abstract our thinking becomes, the more do our words come to stand for meanings and attributes and laws that have come out of the organization of our experience. It is evident that the accuracy of our thinking depends upon these words standing for the _truth_, depends upon whether we have organized our experience in accordance with facts. If our word "Cæsar" does not stand for the real Cæsar, then all our thinking in which Cæsar enters will be incorrect. If our word "justice" does not stand for the real justice, then all our thinking in which justice enters will be incorrect.