In the third Chapter of Zechariah, he has a vision of a trial scene: God is the judge, Satan is the accuser or prosecutor, and Joshua is the first person chosen to be the High Priest for the reconstruction of the Temple in Jerusalem.  Joshua is the accused.  We do not know what he is accused of, but we do know he is found innocent: he (symbolically) goes from being covered with dung to being dressed in fine clothes.  We, too, can be cleansed by God: we can be covered with human excrement and then be transformed into the blameless.