The basic meaning of yi (义) is “reasonable” and “proper.” It has two extended meanings. One is the proper basis and standard for people’s actions. The other is to adjust one’s words or deeds to meet certain standards, under the guidance of moral judgments. Scholars in the Song Dynasty used li (理) or “principles of heaven” to interpret yi, and considered yi to be the reasonable standard defined by the “principles of heaven,” and hoped that people’s words and deeds would fall in line with the “principles of heaven.”