Mencius ; born Meng Ke ; or Mengzi was a Chinese Confucian philosopher who has often been described as the "second Sage" (亞聖), that is, second to Confucius himself. He is part of Confucius' fourth generation of disciples. Mencius inherited Confucius' ideology and developed it further. Living during the Warring States period, he is said to have spent much of his life travelling around the states offering counsel to different rulers. Conversations with these rulers form the basis of the Mencius, which would later be canonised as a Confucian classic.

Confucianism, also known as Ruism or Ru classicism, is a system of thought and behavior originating in ancient China, and is variously described as a tradition, philosophy, religion, theory of government, or way of life. Confucianism developed from teachings of the Chinese philosopher Confucius (551–479 BCE), during a time that was later referred to as the Hundred Schools of Thought era. Confucius considered himself a transmitter of cultural values inherited from the Xia (c. 2070–1600 BCE), Shang (c. 1600–1046 BCE) and Western Zhou dynasties (c. 1046–771 BCE). Confucianism was suppressed during the Legalist and autocratic Qin dynasty (221–206 BCE), but survived. During the Han dynasty, Confucian approaches edged out the "proto-Taoist" Huang–Lao as the official ideology, while the emperors mixed both with the realist techniques of Legalism.