its own particular domicile. Now, such a mental image is termed a concept, and concepts are the material of thought. Thought is the play of consciousness among these concepts—a play which always, in our waking hours, is within definite boundaries and along lines of association. The oddity of our dreams arises from Fig. 7.—The location of the Memory-Pictures of the Word-Image Rose. 1, word-hearing; 2, word-seeing; 3, word-uttering; 4, word-writing memory-picture. the disregard of these lines and boundaries in a semi-conscious state. Many of the concepts are related to one another. Thus the rose is only one of many flowers which you know, and the term "flower" really brings to a focus all the images of the different roses, chrysanthemums, pansies, and pinks and varied objects which the most complete horticultural exhibition can display. The term "flower"—which we may call an abstract term, because it stands, not for a single object, but for a class of different objects with common features—enables us to handle these many mental images easily and communicate the pictures before our minds to others. It is a convenience, then, to use the word; but, nevertheless, it is the mental images, rather than the words, which play the greater part in our thinking.
This has been most ably expressed by the Duke of Argyll, who says: "Images are repetitions of sensation, endowed with all its mental wealth, and consciously reproduced from the stores of memory. Without images we can do nothing in the fields of thought, while with images we can mentally do all things which it is given us to do. The very highest and most abstract concepts are seen and handled by our intellects in the form of voiceless imagery. How many are the concepts roused in us by the forms and by the remembered images of the human countenance! Love and goodness, purity and truth, benevolence and devotion, firmness and justice, authority and command—these are a few, and a few only, of the abstract ideas which may be presented and represented to us in every degree and in every combination by the remembered image of some silent face. What a wealth of concepts is set before us, for example, in the images raised by this single line: