It is certain that the mind is every moment actuated and determined by a plurality of influences, impressions, considerations, thoughts. Almost every act of the will is a resultant of many motives. Our thoughts seldom spring up at the instance of a simple link of association; although it may happen that some one link is sufficing and overpowering, and therefore governs the recall; yet there are almost always others aiding or checking the particular resuscitation. Nevertheless, such complication of antecedents is not inconsistent with the theory of very rapid transitions of attention, there being a certain persisting influence from each separate act. There would, however, be a greater theoretical simplicity, as well as a less appearance of straining a point, if we could suppose that the several conspiring agencies unite in a strictly synchronous whole. Let us next view the question from the side of Activity. Here the circumstance that would most decisively limit the power of attention, and impose an absolute unity (qualified by rapidity of transition) is the singleness of the muscular executive. No one organ can perform two movements at the same instant. Plurality can arise only by the separate organs performing separate actions. In such a case as playing on the pianoforte, there is a very complicated series of muscular exertions. The eyes are occupied with the printed music; both hands are exerted, and every finger performs a separate note; the foot also may be brought into action. At the same time, the ear has to be on the alert. The plurality is here very great; yet it seems much greater than it is. For, at the stage when such a performance is possible, there is a great amount of acquirement; many synchronous groupings have been made by long repetition, so as to dispense with attending to the several acts in separation. The real attention is concentrated on one, or on a very few acts; so few that it is not impossible for them to be commanded by the mere rapidity of transition from one to another. The performer need not attend to the notes of the music, and to the action of the fingers at the same absolute instant of time. It is in the case of commencing some act entirely new to us, that the limitation of the muscular executive is most apparent. In learning the first elements of any accomplishment by imitating a master, the whole attention is concentrated on single movements; at one instant on the master, and the next instant on the act of imitating; the only synchronous addition to this last being the remaining trace of the impression of the model. If the act is complicated, and requires concurring movements of different organs, the attention, at the outset, must be given to one at a time; the conjunction of independent movements is not a primitive, but an acquired power. Previous to acquired groupings, the restriction of the attention to one movement is the rule.