Stories often evoke the pathetic fallacy: characters' emotions tend to be reflected in natural phenomena such as the weather. One reason for such a technique is that description of nature might be one of the few areas of artistic expression where authors enjoy relative freedom from political constraints. Nature as a theme, however, has undergone a transformation. Until the 1990s, man's "revolutionary struggle" is the master of nature, but since then, nature is likened to an external threat. The intended message is that the floods and consequent economic hardship of the 1990s are caused by factors that are not in the control of the government. The 1990s, in general, saw a turn to less romanticised portrayal in North Korean literature. However, despite portrayal of difficulties, stories tend to be optimistic and have happy endings.