Factors. A situation is by definition (page 20) a combination of circumstances, which are the effects of certain causes. To these causes, the term "factors", long in use in the military profession, is customarily applied in many other activities. Through their influence as causes, these factors operate to produce, as their effects, the circumstances which, in combination, constitute the situation. A combination of factors, therefore, gives to each situation its distinctive character, differentiating it from other situations. To maintain an existing situation, it is necessary to preserve, in total effect, the influence of factors already present, or to introduce new factors to offset the influence of any which tend to cause a change. To change the situation, it is necessary to introduce factors which will exert the desired influence; or, change may be effected by altering the influence of factors already present. To say, therefore, that "It depends on the situation", as in the maxim cited (above), is to state that under all circumstances, the proper action depends on, or is determined by, the influence of the factors involved. Any valid rule, or principle, will accordingly take into account the factors applicable to the case. The application of any rule will similarly take into account the influence of the particular factors involved. The danger of the application of such factors to all circumstances, without due circumspection as to their value in the existing situation, lies in the fact that, in any particular combination of circumstances, they do not necessarily carry equal weight. If this view be accepted, it follows that in many situations certain factors may, after mature deliberation, be rejected, or relegated to a relatively inferior status, without detracting from their potential value as fundamental considerations (page 1) in all situations. Value and Limitations of Lists of Principles of War. The human preference for catchwords has, by many writers on the science and art of war, been extended to the attempted condensation of a principle or of several principles into a single all-inclusive word or phrase. As a result, varying lists of abstract nouns and phrases have been advanced to constitute epitomes of the principles of war. Subject to minor differences in number and in designation, the list most frequently encountered comprises The Objective, Superiority, The Offensive, Economy of Force, Movement, Cooperation, Surprise, Security, and Simplicity. To rely on a list of this nature, as a condensation of the fundamentals of war, has been known to cause confusion and to result in failure to recognize the principles which are intended to be brought to mind.