Ren is usually translated as propriety. It means understanding and practicing proper behavior in every possible situation, which of course depends on who you're interacting with, hence the importance of the five relationships. Li is usually translated as ritual and refers to rituals associated with Chinese religion, most of which involve the veneration of ancestors. Which brings us back, in a very roundabout way, to the fundamental problem of how early Chinese historians wrote their history. Traditional Chinese historians were all trained in the Confucian classics, which emphasized the idea that good emperors behaved like good Confucians. Would-be historians had to know these classics by heart, and they'd imbibed their lessons, chief among which was the idea that in order to maintain the mandate of heaven, you had to behave properly and not engage in orgies, or eat your enemies, or eat your enemies while engaging in orgies. In this history, the political fortunes of a dynasty ultimately rest on one man and his actions, whether he behaves properly.