(3) "To evade the enemy." Here again the objective, "evasion of the enemy", is specifically indicated. (4) "To cover friendly and neutral trade." Here the objective, "protection of friendly and neutral trade by the utilization of advantageous covering positions", is more or less inferred. (5) "To escort trade." Here the objective, "protection of trade by escorting it in convoys", is more or less inferred. (6) "To patrol the trade routes." Here the objective, e.g., "protection of trade by patrolling the trade routes", is inferred. (7) "To raid." Here the objective, e.g., "infliction of loss and damage by raiding", is inferred. In the foregoing instances, the action to be taken is indicated in general terms. The extent to which the action may properly be indicated depends on the nature of the problem and is necessarily left to the judgment of the commander. Two possibilities, between which there may be various intermediate cases, are as follows: (a) To destroy the enemy force by simultaneous attacks on the escort and convoy. (b) To destroy the enemy force by an attack with the main force on the escort, following this immediately by an attack on the convoy with a flanking force before the convoy can scatter so widely as to make ineffective the pursuit of any of its units. For a further application, it will be noted that the national policies referred to early in this discussion (page 7) are national courses of action, considered and adopted as methods of attaining national objectives. The expression "courses of action", in the sense of a plan considered or adopted as a solution of the problem, has the defect that it appears to emphasize the action, rather than the paramount component, i.e., the objective. So long as this fact is borne in mind, the limitations of the term "courses of action" need not operate to influence, adversely, the solution of the problem. As noted above, the commander brings to mind courses of action by the mental act of "envisaging", i.e., "viewing with the mind's eye or conceptionally", "seeing as a mental image", bringing fully and distinctively to view. How is this done? Although the time available for the process depends on the particular problem, the process itself is the same for all. During the clarification of the problem, the commander will have entertained certain ideas,--ideas as to such matters as the existing situation, the desired new situation, the possible physical objectives, the relative positions and movements of the forces involved, and related matters. His training and experience cause these ideas to evoke others, which are associated in his mind with problems of the past,--in particular, with the bearing of such ideas on the outcome of those problems.