_Impulses, and References_.—We have now to consider those more fundamental effects upon which stress has been laid above as the true places of the values of the experience. It will be well at this point to reconsult the diagram. The vertical lines which run capriciously downwards from the visual sensations of the words, through their tied imagery and onward to the bottom of the diagram, are intended to represent, schematically, streams of impulses flowing through in the mind. They start in the visual sensations, but the depiction of the tied imagery is intended to show how much of their further course is due to it. The placing of the free imagery in the third division is intended to suggest that while some free images may arise from visual words alone, they take their character in a large part as a consequence of the tied imagery. Thus the great importance of the tied imagery, of the formal elements, is emphasised in the diagram. These impulses are the weft of the experience, the warp being the pre-existing systematic structure of the mind, that organised system of possible impulses. The metaphor is of course inexact, since weft and warp here are not independent. Where these impulses run, and how they develop, depends entirely upon the condition of the mind, and this depends upon the impulses which have previously been active in it. It will be seen then that impulses—their direction, their strength, how they modify one another—are the essential and fundamental things in any experience. All else, whether intellectual or emotional, arises as a consequence of their activity. The thin trickle of stimulation which comes in through the eye finds an immense hierarchy of systems of tendencies poised in the most delicate stability. It is strong enough and rightly enough directed to disturb some of these without assistance. The literal sense of a word can be grasped on the prompting of the mere sight of it, without hearing it or mentally pronouncing it. But the effects of this stimulation are immensely increased and widened when it is reinforced by fresh stimulation from tied images, and it is through these that most of the emotional effects are produced. As the agitation proceeds new reinforcement comes with every fresh system which is excited. Thus, the paradoxical fact that so trifling an irritation as the sight of marks on paper is able to arouse the whole energies of the mind becomes explicable.