We all know the danger there is in putting off calling some one by telephone on being told that "the line is busy", for not infrequently it will happen that several hours will elapse before we think of the matter again {87} and then perhaps it may be too late. If we set a definite time limit with ourselves, however, then our will will prompt us quite as effectively, though quite as inexplicably, at the expiration of that time as it awakes those who have resolved to be aroused at a predetermined moment. We may miss our telephone engagement with ourselves, but we practically never miss an important train, because having deeply impressed upon ourselves the necessity for not missing this, our will arouses us to activity in good time. There is not the slightest necessity, however, for appealing to the unconscious or the subconscious in this. It is true that there is a wonderful sentinel within us that awakes us from daydreams or disturbs the ordinary course of some occupation to turn our attention to the next important duty that we should perform. We know that this sentinel is quite apart from our consciousness; but the power we have of setting ourselves to doing anything is exemplified in very much the same way. When I want a book, I do not know what it is that sets my muscles in motion and brings me to a shelf and then directs my attention to choosing the one I shall take down and consult. It is an unconscious activity, but not the activity of {88} unconsciousness, which is only a contradiction in terms. [Footnote 4]