The first and most manifest principle that has here to be firmly grasped is that anyone sincerely and rationally pursuing any objectives whatsoever must be constantly concerned to monitor their success or failure in approaching and attaining those objectives. Sincerity of purpose absolutely presupposes a strong concern as to whether and how far the purpose entertained has been or is being achieved. This chapter provides insights into intelligence and of rationality. The second principle is a corollary of the first. For a large part of the point of monitoring progress, or the lack of it, is in order to determine whether and when some alteration of approach is called for. The third principle is somewhat more complex. In so far as any of the resources employed to secure the desired results are scarce, the purposers must be concerned to achieve the maximum output of desired results in exchange for the minimum input of scarce resources.