Da'at Elyon ("Higher Knowledge") and Da'at Tachton ("Lower Knowledge") are two alternative levels of the perception of reality. Their terms derive from the
> KETER (above conscious Will) and
> Da'at (conscious Knowledge),
considered two levels of the same unifying principle; the first encompassing, the second internalized within the person. In Kabbalah either Keter or Da'at are listed in the 10 sephirot, but NOT both.
In historical Kabbalah, KETER ("Crown") is the transcendent Divine Will above conscious internalisation, while Da'at ("Knowledge") is the internalised aspect of the same principle, channeling the Creative OHR lifeforce into existence. Consequently, Keter is the "Hidden Knowledge", that becomes revealed in Da'at. Moshe Cordovero lists Keter as the first Sephirah and excludes Da'at, while Isaac Luria excludes Keter as being too transcendent to consider as the first cause of Creation, while substituting Da'at instead. Where Keter is the hidden soul root of the intellectual sephirot, Da'at is the hidden soul root of the emotions that emerge subsequently. Keter is revealed in Intellect, and Da'at is revealed in Emotions.