We could try to answer this by saying that this one is the first in the sense that it is in this Head that the uncertainties are first born, and only thereafter are they drawn into the other Partzufim of Atzilut. However, this does not seem consistent with the clear intent of the words of Rabbi Shimon bar Yochai of blessed memory. For in the Idra Zuta (288a) it is evident that he calls this Head by this name because of its tremendous greatness and glory, and this is why it is concealed. (The implication is not as we tried to answer, that this Head is the first and the root with respect to the uncertainties.
Rather, it is that the Head is unknown because of its very greatness and glory, and this is why it cannot be grasped.) For he says: “The Head that does not know and is not known... that is not attached to Wisdom and not to Understanding...” If so, all of Atzilut is the same – so what special reason is there to call this Head by this name? (The same greatness and glory are also in the other Partzufim as well as uncertainties as to their composition.)