And the outcome? The outcome is that _the stronger side always wins_. Not necessarily the stronger side as we observe it; there may be a more impressive array of ideas on the side that finally gives way; but the side that has the stronger nerve-forces. It is quite certain that _nervous forces or tendencies_—think of the force of habit!—_may guide and direct the course of our thoughts, even though they do not themselves contribute to thought_, even though (that is) they have no sensory or imaginal correlates. We shall have more to say of these guiding tendencies later; meantime let us give an illustration of their power. Suppose that an observer comes into the laboratory to take part in a certain experiment, and that the experimenter carefully explains to him what he is to do. The next day he comes again, and the explanation is repeated. The next day he comes again; this time the experimenter says nothing; the experiment just goes on in the usual way; and so on the following days. Suppose, however, that on the twentieth day the experimenter says: ‘Are you thinking about what I told you to do?’ The observer, fearing that he has done wrong, and feeling very repentant, says: ‘No! to tell the truth I had forgotten all about it; it had absolutely gone out of my mind; have I been making mistakes?’ He had not made any mistake; but his reply shows that a certain tendency, impressed upon his nervous system by the experimenter’s original explanation, had been effective to direct his ideas long after the idea of the explanation itself had disappeared. And what happens here, in a few days’ work in the laboratory, is happening every day of our lives in the wider experience outside of the laboratory. We see, therefore, that there is nothing spontaneous or active about secondary attention. It is merely primary attention over again, but _primary attention under difficulties_; it is a direct consequence of the multiplication of perceptions and ideas, and of the complexity of the nervous system.