Clear ideas on these matters are therefore not wholly useless; besides, the human mind has a general tendency to clearness, and always wants to be consistent with the necessary order of things.

Owing to the great difficulties attending a philosophical construction of the Art of War, and the many attempts at it that have failed, most people have come to the conclusion that such a theory is impossible, because it concerns things which no standing law can embrace.  We should also join in this opinion and give up any attempt at a theory, were it not that a great number of propositions make themselves evident without any difficulty, as, for instance, that the defensive form, with a negative object, is the stronger form, the attack, with the positive object, the weaker—­that great results carry the little ones with them—­that, therefore, strategic effects may be referred to certain centres of gravity—­that a demonstration is a weaker application of force than a real attack, that, therefore, there must be some special reason for resorting to the former—­that victory consists not merely in the conquest on the field of battle, but in the destruction of armed forces, physically and morally, which can in general only be effected by a pursuit after the battle is gained—­that successes are always greatest at the point where the victory has been gained, that, therefore, the change from one line and object to another can only be regarded as a necessary evil—­that a turning movement is only justified by a superiority of numbers generally or by the advantage of our lines of communication and retreat over those of the enemy—­that flank positions are only justifiable on similar grounds—­that every attack becomes weaker as it progresses.

THE INTRODUCTION OF THE AUTHOR

That the conception of the scientific does not consist alone, or chiefly, in system, and its finished theoretical constructions, requires nowadays no exposition.  System in this treatise is not to be found on the surface, and instead of a finished building of theory, there are only materials.

The scientific form lies here in the endeavour to explore the nature of military phenomena to show their affinity with the nature of the things of which they are composed.  Nowhere has the philosophical argument been evaded, but where it runs out into too thin a thread the Author has preferred to cut it short, and fall back upon the corresponding results of experience; for in the same way as many plants only bear fruit when they do not shoot too high, so in the practical arts the theoretical leaves and flowers must not be made to sprout too far, but kept near to experience, which is their proper soil.

Unquestionably it would be a mistake to try to discover from the chemical ingredients of a grain of corn the form of the ear of corn which it bears, as we have only to go to the field to see the ears ripe.  Investigation and observation, philosophy and experience, must neither despise nor exclude one another; they mutually afford each other the rights of citizenship.  Consequently, the propositions of this book, with their arch of inherent necessity, are supported either by experience or by the conception of War itself as external points, so that they are not without abutments.(*)