which activity in war is subject generally, we have already spoken in the first book; we here omit those things which can only be overcome by courage, and maintain also that the activity of mind is only simple and easy in inferior stations, but increases in difficulty with increase of rank, and in the highest position, in that of commander-in-chief, is to be reckoned among the most difficult which there is for the human mind.

45 Of the nature of this knowledge

The commander of an army neither requires to be a learned explorer of history nor a publicist, but he must be well versed in the higher affairs of state; he must know and be able to judge correctly of traditional tendencies, interests at stake, the immediate questions at issue, and the characters of leading persons; he need not be a close observer of men, a sharp dissector of human character, but he must know the character, the feelings, the habits, the peculiar faults and inclinations of those whom he is to command. He need not understand anything about the make of a carriage, or the harness of a battery horse, but he must know how to calculate exactly the march of a column, under different circumstances, according to the time it requires. These are matters the knowledge of which cannot be forced out by an apparatus of scientific formula and machinery: they are only to be gained by the exercise of an accurate judgement in the observation of things and of men, aided by a special talent for the apprehension of both.

The necessary knowledge for a high position in military action is therefore distinguished by this, that by observation, therefore by study and reflection, it is only to be attained through a special talent which as an intellectual instinct understands how to extract from the phenomena of life only the essence or spirit, as bees do the honey from the flowers; and that it is also to be gained by experience of life as well as by study and reflection. Life will never bring forth a Newton or an Euler by its rich teachings, but it may bring forth great calculators in war, such as Condée or Frederick.

It is therefore not necessary that, in order to vindicate the intellectual dignity of military activity, we should resort to untruth and silly pedantry. There never has been a great and distinguished commander of contracted mind, but very numerous are the instances of men who, after serving with the greatest distinction in inferior positions, remained below mediocrity in the highest, from insufficiency of intellectual capacity. That even amongst those holding the post of commander-in-chief there may be a difference according to the degree of their plenitude of power is a matter of course.

46 Science must become art

Now we have yet to consider one condition which is more necessary for the knowledge of the conduct of war than for any other, which is, that it must pass completely into the mind and almost completely cease to be something objective. In almost all other arts and occupations of life the active agent can make use of truths which he has only learnt once, and in the spirit and sense of which he no longer lives, and which he extracts from dusty books. Even truths which he has in hand and uses daily may continue something external to himself. If the architect takes up a pen to settle the strength of a pier by a complicated calculation, the truth found as a result is no emanation from his own mind. He had first to find the data with labour, and then to submit these to an operation of the mind, the rule for which he did not discover, the necessity of which he is perhaps at the moment only partly conscious of, but which he applies, for the most part, as if by mechanical dexterity. But it is never so in war. The moral reaction, the ever-changeful form of things, makes it necessary for the chief actor to carry in himself the whole mental apparatus of his knowledge, that anywhere and at every pulsebeat he may be capable of giving the requisite decision from himself. Knowledge must, by this complete assimilation with his own mind and life, be converted into real power. This is the reason why everything seems so easy with men distinguished in war, and why everything is ascribed to natural talent. We say natural talent, in order thereby to distinguish it from that which is formed and matured by observation and study.

We think that by these reflections we have explained the problem of a theory of the conduct of war, and pointed out the way to its solution.