no sooner has the conscious thought or volition instigated movement A, than A, through the sensation a of its own occurrence, awakens B reflexly; B then excites C through b, and so on till the chain is ended, when the intellect generally takes cognizance of the final result. The process, in fact, resembles the passage of a wave of 'peristaltic' motion down the bowels. The intellectual perception at the end is indicated in the diagram by the effect of G being represented, at G1, in the ideational centres above the merely sensational line. The sensational impressions, a, b, c, d, e, f, are all supposed to have their seat below the ideational lines. That our ideational centres, if involved at all by a, b, c, d, e, f, are involved in a minimal degree, is shown by the fact that the attention may be wholly absorbed elsewhere. We may say our prayers, or repeat the alphabet, with our attention far away.