Kabbalah zu Dewarim 4:32

Rabbi Yehuda said, The scripture proves this. For is written, "For ask now the days that are past...(Devarim 4:32). Up to here, one is permitted to observe, but from here and further, no one can comprehend it.

18. [The beginner] must also know that it is not proper for a student [of Kabbalah] to inquire as to the essence of the three first [sefirot], which constitute intellect, wisdom, and understanding.¹In this enumeration, Keter is referred to as sekhel, i.e., “intellect.” It is furthermore improper to investigate the hidden force which created all that exists.²This is a reference to Keter and Eyn Sof. Since He, His will and wisdom and understanding are one, and they are true qualities of His essence, it is not proper to inquire [into it]. However, from Ḥesed and Gevurah and below, there is no sin in investigating them, for they are qualities which have been emanated in order to direct the lower beings. One who increases his investigation into them is called industrious and will be rewarded. Similar to this [case] is that which is written, You shall surely send forth the mother—which is Binah³Binah, linked with Ḥokhmah, is the “mother” of all the lower sefirot.— and the sons⁴The seven lower sefirot. you will take for yourself (Deut. 22:7), to inquire and investigate. Thus also, inquire now as to the first days (Deut. 4:32).

For that reason Solomon said, "Prepare your work outside, and make it fit for yourself in the field" (Mishlei 24: 27). "Prepare...outside", as it is written, "cry aloud in the streets,". For here, work can be corrected. And this may be sought, as it is written, "For ask now of the days that are past...and from the one side of heaven to the other" (Devarim 4:32).