I've been reading a book on Quantum theories (the ideas, not the math!) On Shabbos, I was commenting to my husband how I saw connections between the ideas in that book and the concepts that I understood of the sefiros, particularly how the world is built in a way that the act of knowing something actually causes it to change. All reality is built not on certainty, but on probabilities. It reminded me of how Keter and Daat somewhat share the same "space" in the Etz Chayim, when one is included, the other is not. We can know, but we cannot know everything, because the act of knowing itself creates limitations.
It seems to me that it is like that with God. We can comprehend Him in a way of "Holy" --in a Godly reality, unmeasured and infinite, our soul entwined in love with Him, or as we see Him manifest within our reality, the Source of wisdom, life, goodness; seeing him in "our terms", which are necessarily limited.
In nusach Ari, there is a line that appears before the Baruch She'amar: "For the sake of the Unification of the Holy One, blessed be He and His Shechina, to unite the name yud-kay with the vav-kay in a perfect union, in the name of all Israel."
It has taken on deep meaning for me. Just as in our world, we live in a reality which is both intrinsically unknowable and exquisitely knowable, so we also understand that we can never truly know God, because Daat itself hides Keter, the Infinite and Holy, where things are not differentiated and bounded.
Uncertainty ( or doubt) is part of all our experience of reality. Yet above it, there is Keter. When we let go, stop quantifying, measuring and looking too closely, when we trust --we experience the Infinite. This too is reality -- in some ways the essence of it: Through trust, we are able to experience the Infinite in a way unfettered and unchanged by attempts to understand it.
... and it is in this place that we truly love God.