Accordingly, when the evaluation of any factor is under consideration, its value as an unknown quantity can be determined to the extent that the values of the other pertinent factors are known. (See page 23, as to the discussion of the quantities in an equation.) The significance of each, in any situation, is therefore determined by the influence of the other factors. The relationships existing among them can best be expressed in the terms of four corollary principles (page 27), next to be discussed. * * * * * For example, questions frequently arise as to what is the appropriate effect to be desired in a particular situation. Whether a desired effect is feasible of attainment, and whether certain consequences, though undesirable, will be acceptable, in view of the gains, can be determined by evaluation of the means available and opposed, influenced by the physical conditions prevailing in the field of action, and of the consequences as to costs. If a desired effect is thereby found to be not feasible of attainment, or to be unacceptable as to consequences, deferment of such effort is indicated. A proper solution in such case would adopt some lesser effect, in conformity with the further aim, feasible of accomplishment, and acceptable as to its consequences. If (with respect to the further aim, mentioned above) the person concerned is acting under the instructions of another, there will frequently be injected into the equation, in addition to the factors already noted, a further effect desired, indicated by higher authority. Such an indication will often operate to narrow the limits of the problem. This is true even if the person concerned is acting wholly on his own initiative and responsibility (pages 29-30). These considerations lead to the formulation of what may be called the corollary principle for determination of the appropriate effect to be desired in human affairs,--as follows: In any human activity, the appropriate effect to be desired (i.e., an end in view, a result to be accomplished) depends on fulfillment of the requirements of Suitability of the end in view, as determined by the factor of the further effect desired (if such further effect is indicated), Feasibility of the effort to attain the end in view, on the basis of comparative resources, as determined by the factors of the means available and opposed, influenced by the factor of the physical conditions prevailing in the field of action, and Acceptability of the results of the effort involved, as determined by the factor of the consequences as to costs. * * * * *