The sky-fire day and earth-fire day in day selection are used to avoid fires or other unfortunate events caused by selecting relevant activities on specific days.
Sky Fire Day refers to a day when it is not suitable to engage in fire-related activities, such as making fires, lighting fires, setting off firecrackers, etc. There are two Heavenly Fire Days in every month, namely Jiayin Day and Xinyou Day. These days are considered unfavorable for fire-related activities.
Land Fire Day refers to a day when it is not appropriate to carry out digging, construction and other land-related activities to avoid causing fires or other unfortunate events. The earth and fire days of each month are Xu, Hai, Zi, Chou, Yin, Mao, Chen, Si, noon and Wei.
To sum up, in order to avoid behaviors that may lead to catastrophic consequences, both Sky Fire Day and Earth Fire Day choose to carry out relevant activities on non-Sky Fire Days and non-Earth Fire Days.