For example: We know that contracted Sefirot are made from His light, but how He acted to conceal and contract His light we cannot say. This is not the case from the Tzimtzum and downwards, where we can say this. For we can specify the different parts of the Partzufim according to when they hold sway, how their desired effects are produced, and what happens to them when they produce new effects. This is not so in the case of Eyn Sof, to Whom we cannot attribute different “parts” or anything of the kind. Accordingly it is impossible to say how He acted or how these Sefirot radiate from Him now, for the way He acts is without limits.
Eyn Sof and the Unknowable Essence Before Creation
Kalach Pitchei Chokhmah 27:12