Part 2: Within each Sefirah lies an inner essence… The inner essence (פנימיות, pnimiyut) is the “interiority” of the Sefirah. Within the Residue, everything follows the Likeness of Man, as will be explained at greater length below (Opening 31), and as discussed earlier (Opening 27) in terms of the soul and the body. This inner essence is the soul (נשמה, neshamah) of the Vessel, and within it is the soul of the soul, just as in the case of man – as will be discussed further below.
...that exists by virtue of the Line of Eyn Sof, blessed be He, which enters into it. For every connection between two things always generates an additional intermediary between them. The inner essence exists by virtue of the Line of Eyn Sof, because it was actually generated by the entry of the Line into the Residue. The truth is that when the Line entered into the Residue, a brilliant radiance shone from it, accommodating itself to the place it entered. This is the soul of the Vessel, and this soul is the underlying root of the individual mental powers (מוחין, mochin) that constitute the particular soul of each of the various Partzufim. For each Partzuf has its own unique mental powers depending on its level. These souls are all a garb for the Line of Eyn Sof, blessed be He, Who does not change in any place. The various mental powers are what each of the different Partzufim receives individually from the Line, but the Line itself is the same everywhere.