When the officer in the General Staff has received a good education in times of peace, in times of war he will quickly become useful in many roles. But without a good education in times of peace, an officer in the General Staff will never achieve anything significant in war. For the latter requires judgement, which is developed through repeated study of military incidents, and a great amount of past facts that we have to keep in mind. These are necessary if we wish, in all cases that occur, thanks to resemblance in circumstances, to be able to judge to some degree the success of an enterprise and avoid the mistakes experience could discover––if we wish to consult all the special circumstances and among the numerous possibilities to choose the most beneficial ones. Nothing in this case is more dangerous than one’s own experience without the understanding with which military history provides us. The few instances of this personal experience now become the yardstick, and all similar occurrences are judged according to them, even if the circumstances and the results are marked by a greater diversity.

I have often seen how deficient, in terms of providing advice, those perform who apply only the facts they have personally experienced. How uncertain and fearful they are in undertaking something the circumstances require, but they have never encountered in the span of their life. These people do not know what one should dare in war. Through reminiscences of a hundred possible but unlikely disasters, they make the general they support anxious. They would, perhaps, never dare an audacious thought because no similar case from history, crowned with success, gives them the necessary confidence. — GERHARD VON SCHARNHORST

https://thestrategybridge.org/the-bridge/2019/4/1/introducing-scharnhorst-the-vision-of-an-enlightened-soldier-on-experience-and-theory