In none of the relations of life does this so frequently happen as in War, where events are seldom fully known, and still less motives, as the latter have been, perhaps purposely, concealed by the chief actor, or have been of such a transient and accidental character that they have been lost for history.

For this reason critical narration must generally proceed hand in hand with historical investigation, and still such a want of connection between cause and effect will often present itself, that it does not seem justifiable to consider effects as the necessary results of known causes.

Here, therefore must occur, that is, historical results which cannot be made use of for teaching.

All that theory can demand is that the investigation should be rigidly conducted up to that point, and there leave off without drawing conclusions.

A real evil springs up only if the known is made perforce to suffice as an explanation of effects, and thus a false importance is ascribed to it.
Besides this difficulty, critical inquiry also meets with another great and intrinsic one, which is that the progress of events in War seldom proceeds from one simple cause, but from several in common, and that it therefore is not sufficient to follow up a series of events to their origin in a candid and impartial spirit, but that it is then also necessary to apportion to each contributing cause its due weight.