"Who raised up one from the east"
Rabbi Shimon begins by explaining that the "Who" in the scripture refers to the supernal world, Binah. The entire secret of the Faith (Malchut) begins from Zeir Anpin, from where the Light becomes revealed. The discussion moves to righteousness, which rules over all the worlds to guide them and to maintain them as necessary. Righteousness never turns away from Zeir Anpin and never keeps silence. Rabbi Shimon ends by saying that the Holy One has illuminated the way because of Elazar, Rabbi Shimon's son, who calls to the supernal Light and is not silent.
Like the moon, Malchut is barren, lacking any Light of her own. For this reason, Malchut never turns away from Zeir Anpin, so that she may constantly catch the Light shines from this supernal sphere. Man, unaware of this cosmic truth, has constantly turned away from the Light, seduced by the illusionary pleasures presented to him by the Other Side.
Here we become cognizant of our Malchut nature, the realization that we have no Light of our own. And as the moon is compelled to faithfully face the sun to receive her light, the entire realm of Malchut is suddenly propelled by the calling and righteousness of Rabbi Elazar. She (Malchut) turns on her spiritual axis and comes face to face with the upper world to receive the full radiance of Light emanating from the Creator.