Now, just as the worlds of Atzilut and Briyah arose in G-d’s simple and essential desire (Ratzon HaPashoot), so too, Yetzirah arose in His simple essential desire. From Malchut of Malchut of Briyah is drawn Atik and Arich of Yetzirah (The pleasure and desire for the world of Formation). Here too, there is a Masach between Briyah and Yetzirah just as there is between Atzilut and Briyah. In other words, just as there is no comparison between thought and emotion and there must, therefore, be a Tzimtzum in between them, so too, between Briyah (thought) and Yetzirah (the emotions) there is a Masach.
Just as above, Keter Malchut of Briyah is the desire to actualize the world of Briyah, so too, Keter Malchut of Yetzirah is the desire to actualize the world of Yetzirah. From this pleasure and desire for Yetzirah (emotions), there is drawn the intellect for the desire, i.e. Chochmah and Binah of Yetzirah, which are called “Abba & Imma of Yetzirah”. From Abba and Imma of Yetzirah, (The intellect for the desire for Formation), is drawn the emotions of Formation, which is called Zeir Anpin of Yetzirah. From Zeir Anpin of Yetzirah, The emotions for Formation are drawn into the actualization of the world of Yetzirah, (Malchut of Yetzirah). As mentioned before Malchut is the letters and vessels for the light. Therefore, Malchut of Yetzirah is the letters of actualization and revelation of the light of the world of Yetzirah. Therefore, Malchut of Yetzirah is the source of the actual existence of the souls and angels of the world of Yetzirah.