In the eighteenth and nineteenth centuries Manchu rule brought into a sharper focus the largely unformulated constitutional theory which had underlain the Chinese imperial society for nearly twenty centuries. With the sharper demarcation of rulers and ruled, the Manchus had to make frequent and overt use of legal authority over the ideology. The Chinese read of the sanction of rebellion in their own classics; they could turn to their histories for a description of the ignoble origins of their present masters. The dynasty turned therefore to literary censorship and ordered extensive excisions from all writings scholarly, artistic, or other, which might weaken the prestige of their house.[13] They ordained a most rigid and dogmatic interpretation of the classics so as to suit their purposes. This the Chinese met with sharp criticism. The literary struggle did much to weaken the scholastic class and to deprive the Manchus of academic supporters. At the same time it deprived the peasant Chinese of their natural leaders, with the consequence that secret and half-literate political associations faced an arbitrary government military in character. The old Chinese system remained, but it became more and more of a form with every generation. The theory of moral agency and ideological control was defamed by the very presence of the barbarian garrisons. The barbarians themselves weakened so much that in the later days of the Manchu Empire the military occupation became a myth instead of being a political fact. For the time being, however, Manchu military organization acted as a force-displaying agency until the scholars and the less favored classes of society were able to combine in a revolution. Pacific government, government by moral agency, derives its greatest powers from assent and agreement; it thrives on symbolization and is never necessarily dependent upon the display of outright force. Government by force, on the other hand, remains effective almost in proportion to the exercise and vigor of that force; stereotyped and ritualized, it is essentially weak. Purely ceremonial administration and offices may be a burden on the body politic, yet their dignity may make up for their lack of efficiency. But an army that cannot fight is an object of ridicule, and its very presence a challenge to the resources of intelligence.