Bamboo, one of the "Four Gentlemen" (bamboo, orchid, plum blossom and chrysanthemum), plays such an important role in traditional Chinese culture that it is even regarded as a behavior model of the gentleman. As bamboo has features such as uprightness, tenacity, and modesty, people endow bamboo with integrity, elegance, and plainness, though it is not physically strong. Countless poems praising bamboo written by ancient Chinese poets are actually metaphorically about people who exhibited these characteristics. An ancient poet, Bai Juyi (772–846), thought that to be a gentleman, a man does not need to be physically strong, but he must be mentally strong, upright, and perseverant. Just as a bamboo is hollow-hearted, he should open his heart to accept anything of benefit and never have arrogance or prejudice.