shì yì shì yì 世异事异
When Times Change, So Do Social Conditions.
This means adapting one’s approach to changing conditions. The saying is from the chapter “The Five Vermin” in Hanfeizi. According to this work, many changes in social conditions occur in response to changing times, and people should adjust their approaches accordingly to keep up with new developments instead of just following past practices. Most scholars of the Legalist School held similar views. This argument was a source of inspiration for those who pursue reform and modernization endeavors.
When social conditions change, the way of doing things will be different. (The Theories of Shang Yang)
In the ancient past, King Wen of Zhou only had a territory of 100 square li between Feng and Hao. By practicing benevolence and righteousness, he pacified the Rong tribes to the west and subsequently became the ruler of all under heaven. King Yan of Xu held a piece of land covering an area of 500 square li east of the Hanshui River. He also practiced benevolence and righteousness, and thirty-six states paid tribute to him with offers of territory. King Wen of Jing feared the King of Xu would present a threat to him; he then attacked Xu and occupied it. Thus, King Wen practiced benevolence and righteousness and ruled all under heaven, whereas King Yan practiced the same principle but lost his kingdom. That is because benevolence and righteousness were applicable in ancient times but not today. For that reason, it is said that when social conditions change, the way of doing things will be different. (Hanfeizi)