But this conduct of war, conditioned by the peculiar relations of States, and of the military force employed, must still always contain in itself something more general, or rather something quite general, with which, above everything, theory is concerned.
The latest period of past time, in which war reached its absolute strength, contains most of what is of general application and necessary. But it is just as improbable that wars henceforth will all have this grand character as that the wide barriers which have been opened to them will ever be completely closed again. Therefore, by a theory which only dwells upon this absolute war, all cases in which external influences alter the nature of war would be excluded or condemned as false. This cannot be the object of theory, which ought to be the science of war, not under ideal but under real circumstances. Theory, therefore, whilst casting a searching, discriminating and classifying glance at objects, should always have in view the manifold diversity of causes from which war may proceed, and should, therefore, so trace out its great features as to leave room for what is required by the exigencies of time and the moment.
Accordingly, we must add that the object which every one who undertakes war proposes to himself, and the means which he calls forth, are determined entirely according to the particular details of his position; and on that very account they will also bear in themselves the character of the time and of the general relations; lastly, that they are always subject to the general conclusions to be deduced from the nature of war.