The applicatory method[16] is used frequently by preference as the system of instruction, but its creator, General von Verdy du Vernois, considers it merely a complement of the deductive method, on which it is predicated and based. “The weakness of the whole applicatory system of instruction lies in the fact that a textbook based upon it, although written by a master hand, can portray only isolated examples, and that these, studied again and again, soon lose their value in the same manner as a maneuver terrain that has become too well known. For, although we ordinarily find principles represented in a connected form, this method of instruction can only convey them in a fragmentary manner in connection with the details of the events described.”[17] The success of the applicatory method depends largely upon the individuality of the instructor, and owes its charm to the personal intercourse between teacher and pupil. Only an expert, who possesses a thorough professional knowledge, who is master of his subject, and who has the faculty of presenting it skillfully, will be able to produce imaginary scenes which faithfully represent reality and are free from objectionable features. By constant practice with specific cases, under the most diverse situations, the nature of war may in this way be taught and initiative developed as well as facility acquired in issuing appropriate, clear, and concise orders. One danger of using nothing but the applicatory method must be noted. The instructor, as representative of a definite theory, finds it comparatively easy to select the conditions governing a specific case in such a way that the theory which he represents necessarily appears to be the correct one. This is especially true when the director of an applicatory problem determines the action of the opposing side. The two methods (the applicatory, or inductive, and the deductive) must be so supplemented that the lesson in tactics clearly illustrates the purpose and object of a tactical operation and allows of the attainment of a thorough knowledge of the means necessary to gain that object.[18] “He who is able to understand the situation, has a definite purpose in view, and knows the means with which to carry out that purpose, will, by a simple mental operation, arrive in each particular case at an appropriate decision, and will be able, furthermore, to carry out that decision, provided he does not lose his head. If a clear comprehension of the purpose in view and of the means for carrying out that purpose lie within the sphere of theory, the estimate of the situation and the decision are governed by the circumstances of the particular case. Should the training in this direction lie outside the sphere of theory, it will logically belong to the domain of the applicatory method of instruction. The two methods must, therefore, supplement each other. [16] See KÜHNE, _Kritische Wanderungen_, 4 and 5, Preface p. 5.