But this is only true with a limitation. The association of ideas as such does not do more to lighten the task of the brain in apprehending and in judging than does the uprising throng of memory-images in the neighbourhood of the excited centre. The presentations, which the association of ideas calls into consciousness, stand, it is true, in somewhat closer connection with the phenomenon which has sent a stimulus to the brain, and by the latter has been perceived, than do those occurring in the geometrical circuit of the stimulus-wave; but even this connection is so slight, that it offers no efficient help in the interpretation of the phenomenon. We must not forget that properly all our perceptions, ideas, and conceptions are connected more or less closely through the association of ideas. As in the example cited above the sensation of blue arouses the ideas of the sky, the sea, a blue eye, a uniform, etc., so will each of these ideas arouse in its turn, according to Wundt’s law, ideas associated with them. The sky will arouse the idea of stars, clouds and rain; the sea, that of ships, voyages, foreign lands, fishes, pearls, etc.; blue eyes, that of a girl’s face, of love and all its emotions; in short, this one sensation, through the mechanism of the association of ideas, can arouse pretty well almost all the conceptions which we have ever at any time formed, and the blue object which we have in fact before our eyes and perceive, will, through this crowd of ideas which are not directly related to it, be neither interpreted nor explained. In order, however, that the association of ideas may fulfil its functions in the operations of the brain, and prove itself a useful acquisition to the organism, one thing more must be added, namely, attention. This it is which brings order into the chaos of representations awakened by the association of ideas, and makes them subserve the purposes of cognition and judgment. What is attention? Th. Ribot[74] defines this attribute as ‘a spontaneous or an artificial adaptation of the individual to a predominating thought’. (I translate this definition freely because too long an explanation would be necessary to make the uninitiated comprehend the expressions made use of by Ribot.) In other words, attention is the faculty of the brain to suppress one part of the memory-images which, at each excitation of a cell or group of cells, have arisen in consciousness, by way either of association or of stimulus-wave; and to maintain another part, namely, only those memory-images which relate to the exciting cause, _i.e._, to the object just perceived.