大旱則雩祭而請雨，大水則鳴鼓而劫社，何也？
When droughts occur, yu sacrifices42 are performed to pray for rain. When floods occur, drums are beaten in order to put fright into the soil god.
曰：陽者，陰之長也。
Why is this?
其在鳥，則雄為陽，雌為陰；其在獸，則牡為陽而牝為陰；其在民，則夫為陽而婦為陰；其在家，則父為陽而子為陰；其在國，則君為陽而臣為陰。
故陽貴而陰賤，陽尊而陰卑，天之道也。
It is because yang is an outgrowth of yin. Among birds, roosters are yang and hens are yin; among animals, rams are yang and ewes are yin. Among people, husbands are yang and wives are yin. In families, fathers are yang and sons are yin. In states, rulers are yang and court officers are yin. So it follows that yang occupies a high position and yin a mean position. Yang is exalted and yin debased—this is the Way of Heaven. Yu 雩: an ancient sacrifice performed to pray for rain.