In Kabbalah, it explains that Hashem’s Light and Power come into the worlds in two ways called ‘circles’ and ‘lines.’
‘Circles’ refers to an encompassing and transcendent Light that is not limited to an orderly structure, similar to how a circle has no beginning or end. ‘Lines’ refers to a Light that is limited and defined to a certain structure or system, where there must be an orderly progression of one thing coming before the next, like a line.
The analogy for this is the soul powers in a person: The subconscious soul powers, like the subconscious potential for wisdom and kindness etc., are like ‘circles,’ they don’t exist in a limited structured manner like a line, rather as undefined and unlimited potential for all types of wisdom or kindness. The conscious soul powers are like line, they work in a systematic orderly progression; like the orderly progression of how an idea is understood or how a feeling is developed.
Another reason that these subconscious soul powers are called ‘circles’ is because they encompass in themselves and affect whatever is revealed from them on a conscious level, as if the subconscious soul power is a circle encompassing the line of conscious knowledge or emotion.
Similarly, Hashem’s Light comes down in these two modes of ‘circles’ and ‘lines.’ The levels that precede Atzilus, which are generally known as Kesser, encompass the levels of the Four Worlds of Atzilus, Beriah, Yetzira, and Asiya, like the subconscious mind and heart encompass the conscious mind and heart.
Now, in a line, there is the beginning and the end. The beginning is the ‘head’ of the line, and the end is the ‘feet’ of the line. In conscious knowledge, the initial flash of insight is the ‘head’ of the idea, and the knowledge of its practical application is the ‘feet’ of the idea.
In a certain sense, the subconscious mind equally encompasses the ‘head’ of conscious knowledge, the initial insight, together with the ‘feet’ of that knowledge, in practical application.
Similarly, the levels of Kesser, including the level of Arich Anpin, encompass all the levels of the Four Worlds equally, from Wisdom of Atzilus, to physical actions in Asiya.
This is called the ‘circles,’ i.e., encompassing aspects of Arich Anpin, surrounding the ‘feet,’ i.e., lowest level, of Asiya, which is the physical action and physical objects in Asiya.
Meaning, through the Mitzvah of Milah there is drawn down and revealed Hashem’s Light that comes from the Lofty Makkif-Encompassing level of Kesser, which includes in itself the worlds of Atzilus, Beriah, Yetzira, and Asiay, thus making it possible to bring down Hashem’s Will even into physicality, into parchment and the like.
