ideologies battle, theres a weird russian book on this, its disguised as spiritual knowledge but it talks about trends or movements, old systems directly and indirectly protect the status quo, in order to change systems people have to be influenced in their everyday life, but it cannot be done by force because the old system and its allys will swing back and try to restablish equilibrium. the best idea doesn't always win but the most talked about tends to have the upper hand, until it weakens, then the next system comes along and finally ko's it