This is one of the guiding principles in the implementation of the Zhou rites, as was recorded in The Book of Rites, a Confucian classic. The rituals were so cumbersome at the time that even the nobility found it difficult to observe them strictly. The commoners, mostly poor and busy earning their livelihood, were incapable of affording the money and energy needed to fulfill the numerous ceremonial requirements. Therefore, it was stipulated that observation of the rites not be mandatory for common people. It was only used to inspire them towards self-improvement. Although the Zhou rites had long since become history, the spirit of benevolence and tolerance shown in this principle was upheld in the ages that followed.