When evil is rampant, there is a fierce struggle between good and evil. Taking tonic will make the yang more rampant, strengthen the exterior and interior of defense, and make the evil spirits disappear, that is, close the door and guard the bandits.
When the conflict between good and evil reaches a certain period, both righteousness and evil spirits decline, and righteousness is powerless to drive away evil spirits. Therefore, at this time, it is necessary to supplement healthy qi in order to ward off evil spirits.