While Confucius wrote at a time and place different from those of Socrates, Plato, and Aristotle, much of his thoughts relate closely with the three Greek thinkers. In his Analects, Confucius emphasizes the morality of the government and of individuals. Everything derives from the efforts of individuals. It was in their ability to perfect themselves, and in doing so would true change occur. This change was directed as a return to the perfection of earlier times. An extension of this is the idea of ancestor worship, an important aspect of Confucius's philosophy. In addition, the pursuit of harmony was perceived as virtue in Confucianism.
While these ideas may not seem very relatable to those of Socrates, Plato, and Aristotle, there are numerous threads connecting them. Much of Socrates's thought is lost; the only real source of his philosophical outlook is through the words of his student, Plato. Socrates, like Confucius, formulated a system built on social concerns, particularly those relating to justice. From what can be gleaned from his thought, he spoke little, if at all, about natural concerns. Like his Chinese predecessor, Socrates focused on human concerns.
Plato, rather than Socrates, offers a more elaborate and developed system of thought, and much of it can be related to Confucius's thought. In The Republic, for example, Plato discusses many of the questions which concerned Confucius. Like Confucius, Plato was concerned with the nature of government, particularly in terms of justice and morality, and he also posited that social change derives from the efforts of individuals to better themselves. Like Confucius, Plato argues that an improvement in an individual's moral goodness will lead to an improvement in the morals of a society.
Aristotle, unlike Confucius, Socrates, and Plato, had much more varied philosophical interests. He writings cover not only human concerns but also the natural world. He wrote works on ethics and politics, and a number of his ideas relate to those of Plato, Socrates, and Confucius. In his Nichomachean Ethics, Aristotle argues that all human action is aimed toward a specific purpose, or the "good." Unlike Confucius and Plato, Aristotle approaches the question of ethics rather scientifically, breaking down human nature into two impulses: the rational and the nonrational.
The rational, as the name indicates, deal with purely intellectual matters. Morality, and its improvement, cannot be discussed or pursued unless the rational and the non-rational were included. The non-rational comprises "vegetative functions," which essentially relates to those functions not associated with the intellect. In Confucius, Socrates, and Plato, they place much less emphasis on the natural and more on the intellectual (an aspect of the human). Like his three predecessors, however, Aristotle argues that the "good" is essentially a balance between two extremes.
Much of their similarities can be seen in specific works, particularly Confucius's Analects, Plato's Republic, and Aristotle's Nichomachean Ethics.