The opening sentence of the Maoni Secret Guest was: " A gentleman who is strong in nature is always striving for self-improvement; a gentleman who is strong in geography is always carrying things with virtue." This sentence came from the Book of Changes, one of the classic sayings in ancient Chinese philosophy. It emphasized that human beings should constantly strive for progress and excellence, but also pay attention to moral cultivation, conform to nature, and respect the laws. This sentence was widely used in spy novels as the opening of the novel, leading the readers into the world of the novel.