The Navajo believe this ghost to be a mediator between man and his creator. Day and night, rain, wind, sun, and other natural forces are all under Yeiis’ power. The Yei’bi’chai, grandfather spirit or “talking God,” is a particularly special sort of Yeii who can speak to a man and teach him how to live in peace with all living things by following certain simple rules of behavior to conserve and use only what he needs to exist. The “Rainbow Man,” a Yeii directing the rainbow and bestowing beauty on all individuals in harmony, is a symbol of the accomplished harmony.