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."