These formal tests are not to be confused with the preliminary tests already given by the commander to each course of action as it occurs to mind. Necessarily, there is such a preliminary test, because the commander does not wish to entertain inappropriate courses of action. For a competent commander, the mental power to envisage solutions of a military problem is so much grounded in experience that appropriate suggestions are most likely to occur; in fact, discriminating thought with respect to military problems is natural for such a commander. This immediate discrimination is, however, merely the preliminary test. It prevents setting up wooden soldiers only to knock them down, but it does not necessarily subject each suggested solution to a thorough analysis. The commander may apply the tests to each course of action as it occurs to his mind. This procedure, however, may be rendered impossible by the fertility of suggestion; perhaps the commander has thought of several courses of action practically simultaneously. It is, therefore, often better to apply the tests to all of the courses of action, in turn, during a separate stage of the process of thinking. This is the procedure indicated herein, as standard, by the sequence of steps in this section of the Estimate. The process of testing, itself, may bring to mind those combinations of courses of action previously referred to (page 93). The degree of formality characteristic of the tests varies with the nature of the problem. In a broad strategical estimate, these tests may be searching and extensive; they may then consume much time. Yet, if the commander, in making a quick decision of great urgency in actual battle, does not apply the tests, he may adopt a course of action leading to tragic results. In such circumstances, the competent commander, under pressure of danger, grasps the whole complex situation without loss of time. He is not carried away by any chance impressions. He does not overlook what is significant in the unexpected event. Because he is mentally prepared for the exercise of command (page 114) he sees things in their true proportions (page 4). In immediate response, he coolly chooses the same course of action which he would adopt if he had time for careful deliberation. In making the tests, the commander rejects courses of action found unsuitable in that they will not, if successfully prosecuted, contribute to the attainment of the objective. He does not, as yet, reject courses of action found to be promising of only partial accomplishment of the task, because there may be later possibilities of effecting combinations to this end. The commander also rejects, at this point, courses of action found to be infeasible of accomplishment. He is careful, however, not to reject, abruptly, any which may later be found to be feasible in combination with other courses.