Q: What and where is the world of “Ein Sof”?
A: We must refrain from interpreting “Ein Sof” (infinity) as a term of time or place. “Ein Sof” is something endless, unlimited by action or attributes; hence the name “Ein Sof.”
Spirituality has no time or space. Therefore, these two limitations of our world do not apply to the spiritual world. For that reason we cannot imagine spirituality for what it is. We cannot imagine a cup, that, although filled to the rim, it is still in a state of endless filling (naturally, everything is measured according to the cup itself, because we measure everything with regards to the receiver).
Malchut, the soul, corrects itself through the worlds. The worlds are degrees of concealment or manifestation of Light. Time and again, the soul receives desires (which are the vessels) and Light (the power to correct the desire) from the degrees.
By using that desire and the Light of correction, the soul, by correcting itself, seemingly rises to the same degree from which it received the power and desire to correct. All and all there are five worlds, within which there are five Partzufim, with five inner Sefirot. Together they make up 125 degrees. But there are still an enormous number of transitory situations.
Q: You write that a “world” is also every phase of Malchut, of the souls, the collective vessel. Is Malchut a Sefira or a world?
A: Malchut is the tenth Sefira, the last one after the nine Sefirot of direct Light that extend from the Creator. Malchut receives the Light from all other nine Sefirot and divides in ten parts. Those ten parts of Malchut are the worlds and everything in them.
Q: Is creation Malchut? And what are all the upper Sefirot?
A: All nine other Sefirot before Malchut (also called the “Upper Nine”) are attributes of the Light. Malchut must resemble those nine Sefirot. The extent of resemblance between Malchut and the nine Sefirot, which are the attributes of the Creator, depends on the power of the screen in Malchut. But the resemblance of Malchut to the nine Sefirot exists even with the smallest screen.
Therefore, even a minimal screen should make Malchut resemble all nine other Sefirot. Thus, any spiritual attainment is comprised of a whole picture (which includes all the Sefirot). A picture with a minimal screen can be comprised of a small number of shades or details, but it still makes for a relative picture of all nine Sefirot.
Just as, when we are born, we perceive with all five senses, regardless of whether we are adults or children, the power (depth) of the attainment depends on the power of the screen.