German’s self-assurance is worst of all, stronger and more repulsive than any other, because he imagines that he knows the truth

From War and Peace by Leo Tolstoy.  Book 9, Chapter 10.  

Pfuel, always inclined to be irritably sarcastic, was particularly disturbed that day, evidently by the fact that they had dared to inspect and criticize his camp in his absence. From this short interview with Pfuel, Prince Andrew, thanks to his Austerlitz experiences, was able to form a clear conception of the man. Pfuel was one of those hopelessly and immutably self-confident men, self-confident to the point of martyrdom as only Germans are, because only Germans are self-confident on the basis of an abstract notion—science, that is, the supposed knowledge of absolute truth. A Frenchman is self-assured because he regards himself personally, both in mind and body, as irresistibly attractive to men and women. An Englishman is self-assured, as being a citizen of the best-organized state in the world, and therefore as an Englishman always knows what he should do and knows that all he does as an Englishman is undoubtedly correct. An Italian is self-assured because he is excitable and easily forgets himself and other people. A Russian is self-assured just because he knows nothing and does not want to know anything, since he does not believe that anything can be known. The German’s self-assurance is worst of all, stronger and more repulsive than any other, because he imagines that he knows the truth—science—which he himself has invented but which is for him the absolute truth.

Pfuel was evidently of that sort. He had a science—the theory of oblique movements deduced by him from the history of Frederick the Great’s wars, and all he came across in the history of more recent warfare seemed to him absurd and barbarous—monstrous collisions in which so many blunders were committed by both sides that these wars could not be called wars, they did not accord with the theory, and therefore could not serve as material for science.

In 1806 Pfuel had been one of those responsible, for the plan of campaign that ended in Jena and Auerstädt, but he did not see the least proof of the fallibility of his theory in the disasters of that war. On the contrary, the deviations made from his theory were, in his opinion, the sole cause of the whole disaster, and with characteristically gleeful sarcasm he would remark, “There, I said the whole affair would go to the devil!” Pfuel was one of those theoreticians who so love their theory that they lose sight of the theory’s object—its practical application. His love of theory made him hate everything practical, and he would not listen to it. He was even pleased by failures, for failures resulting from deviations in practice from the theory only proved to him the accuracy of his theory.