Sincerity is among the core concepts of the Confucian school of thought.
Basically, it means truthfulness without deceit. Confucians believed that
sincerity is the essence of the "way of heaven" or "principles of heaven," a
basis on which everything else is built. At the same time, sincerity is also the
root and foundation of morality. All moral deeds must be conducted on the
basis of sincerity from the bottom of the heart. Otherwise, they are nothing
but pretensions. The Doctrine of the Mean maintains, "Nothing can be achieved
without sincerity." Sages are sincere by nature. Therefore, their words and deeds
are naturally consistent with the "way of heaven" and the "principles of heaven."
Junzi (a man of virtue) upholds sincerity as his goal for moral attainment and an
approach to achieving the "way of heaven" and the "principles of heaven."