That theory it will be unprofitable to labour further at this point. Let it suffice for the present to mark that it gives us a conception of war as an exertion of violence to secure a political end which we desire to attain, and that from this broad and simple formula we are able to deduce at once that wars will vary according to the nature of the end and the intensity of our desire to attain it. Here we may leave it to gather force and coherence as we examine the practical considerations which are its immediate outcome. * * * * * CHAPTER TWO NATURES OF WARS-- OFFENSIVE AND DEFENSIVE * * * * * Having determined that wars must vary in character according to the nature and importance of their object, we are faced with the difficulty that the variations will be of infinite number and of all degrees of distinction. So complex indeed is the graduation presented that at first sight it appears scarcely possible to make it the basis of practical study. But on further examination it will be seen that by applying the usual analytical method the whole subject is susceptible of much simplification. We must in short attempt to reach some system of classification; that is, we must see if it is not possible to group the variations into some well-founded categories. With a subject so complex and intangible the grouping must of course be to some extent arbitrary, and in some places the lines of demarcation will be shadowy; but if classification has been found possible and helpful in Zoology or Botany, with the infinite and minute individual variations with which they have to deal, it should be no less possible and helpful in the study of war. The political theory of war will at any rate give us two broad and well-marked classifications. The first is simple and well known, depending on whether the political object of the war is positive or negative. If it be positive--that is, if our aim is to wrest something from the enemy--then our war in its main lines will be offensive. If, on the other hand, our aim be negative, and we simply seek to prevent the enemy wresting some advantage to our detriment, then the war in its general direction will be defensive.