Some key concepts in Confucian thought
A simple way to appreciate Confucian thought is to consider it as based on varying levels of honesty. The biography of Confucius deals with the origins of this view. In practice, rituals of Confucianism accrued over time and matured into the following form:

Lǐ (禮) — ritual. This originally meant "to sacrifice." From this initial religious ceremonial meaning, the term was soon extended to include secular ceremonial behaviour, and then took on an even more diffuse meaning, that of the propriety or politeness which colours everyday life. Rites were codified and treated as an all-embracing system of norms. Confucius himself tried to revive the etiquette of earlier dynasties, but in later Confucian tradition, he himself was regarded as the great authority on ritual behaviour.
Xiào(孝) — filial piety. This was considered among the greatest of virtues, and had to be shown towards both the living and the dead. The term "filial", meaning "of a son", denotes the respect and obedience that a son should show to his parents and, traditionally, especially to his father. This relationship was extended by analogy to a series of five relationships: those between father and son, ruler and subject, husband and wife, elder brother and younger brother, and that between friends. Specific duties were prescribed between each of the participants in these sets of relationships. Such duties were also extended to the dead, and this led to the veneration of ancestors, to which the living stood as sons to their fathers. At this point we can see xiào almost imperceptibly fading into lǐ, e.g. the precise regulations on the length and manner of mourning on the death of a family member. In time, filial piety was also built into the Chinese legal system: a criminal would be punished more harshly if the culprit had committed the crime against a parent, while fathers exercised enormous power over their children. Much the same was true of the other unequal relationships. The main source of our knowledge of the importance of filial piety is The Book of Filial Piety, a work which is attributed to Confucius, but was almost certainly written only in the third century B.C. Nevertheless, filial piety has continued to play a central role in Confucian thinking to the present day.
Zhōng(忠) — loyalty. This was the equivalent of filial piety on a different plane, that of the relationship between ruler and minister. It was particularly relevant for the social class to which most of Confucius's students belonged, because the only way for an ambitious young scholar to make his way in the world was to enter the civil service of a ruler. Like filial piety, loyalty was often subverted by the autocratic regimes of China. Confucius had advocated a sensitivity to the realpolitik of the class relations that existed in his time: he did not propose that "might makes right", but that a superior who had received the "Mandate of Heaven" (see below) should be obeyed because of his moral rectitude. But this was soon reinterpreted and became a doctrine which demanded blind, unquestioning obedience to the ruler from the ruled. It is generally held that Confucius would not have supported this — he was far too subtle a thinker for that.
Rén(仁) — humaneness. Confucius was concerned with people's individual development, but he maintained that this is realized within the context of human relationships. Ritual and filial piety are the ways in which one should act towards these others, but the underlying attitude is one of humaneness. Unlike ritual, it is not the kind of thing that can be easily defined or identified in a particular person. It is perhaps best expressed in the Confucian version of the Golden Rule, which is phrased in the negative: "Do not do to others what you would not like them to do to you." Rén also has a political dimension; if the ruler lacks it, it will hardly be possible for the subjects to behave humanely. This, in fact, is the basis of the entire Confucian political theory: it presupposes an autocratic ruler, who is then exhorted to refrain from acting inhumanely towards the subjects. An inhumane ruler runs the risk of losing the "Mandate of Heaven" — the right to rule. Such a mandateless ruler need not be obeyed. But a ruler who reigns humanely and takes care of the people is to be obeyed strictly, for the very fact of this benevolent dominion shows that the ruler has been mandated by heaven. Heaven (Shang Ti or T'ien) here is a vague concept of an impersonal superior reality, much as westerners might say, "Heaven help us" (although some scholars interpret the concept theistically). Confucius himself had little to say on the will of the people, but his leading follower Mencius did state on one occasion that the people's opinion on certain weighty matters should be polled.
Jūnzǐ(君子) — the perfect gentleman. The gentleman is the ideal towards which all Confucians strive. (In modern times, the masculine bias in Confucianism has weakened, but the same term is still used.) The term literally means "son of a ruler," and there was a hereditary elitism inherent in the gentleman concept, but besides this, gentlemen were also expected to act as moral guides to the rest of society. Gentlemen are those who cultivate themselves morally, who participate in the correct performance of the rites, who show filial piety and loyalty where these are due and who have cultivated humaneness. The great exemplar of the gentleman is Confucius himself. It is indeed one of the great tragedies of his life that he was never awarded the high official position which he desired, and from which he wished to demonstrate the general well-being that would ensue if humane persons ruled and administered the state. The opposite of the Jūnzǐ was the Xiǎorén (小人), literally 'small person.'