Part 2: This is because of the need for gradation, so that Zeir Anpin should only receive the lights at a low strength… In other words, Zeir Anpin receives only the offspring of the offspring – the lowest part of the lowest part. For Malchut of Abba and Imma is their lowest part, but even this Zeir Anpin cannot receive in its entirety, only the lowest part of it – Malchut of Malchut, which is the Second Israel Sabba-Tevunah. These become the Tzelem of Zeir Anpin.
And even that Tzelem does not enter into Zeir Anpin’s interior with the exception of its lowest part, the Tzaddi – Malchut of Malchut of Abba and Imma. Yet the purpose of this gradation is obvious. For Zeir Anpin can only ever receive his interior soul – even in the Second Maturity – from Malchut of Abba and Imma, because only the lowest part of the upper Partzuf can become the interior soul of the lower Partzuf, and in this case Israel Sabba-Tevunah are the lowest part of the upper Partzuf. Even this Zeir Anpin can only receive at certain times, and thus there are times when he receives more and times when he receives less. Accordingly there had to be a gradation whereby at a time when he receives less he only takes the lowest part of this Malchut, whereas at a time when he receives more he takes the whole of this Malchut.