...and is built of MaH and BaN. For all of Atzilut is built of MaH and BaN. In the case of Arich Anpin, this MaH and BaN are its male and female aspects.
Arich Anpin is the root of all the rest of Atzilut... The difference between Arich Anpin and the other Partzufim is that each of the other Partzufim is a separate branch. Even though in terms of their development they emerge from one another, the truth is that they are not branches of one another. Rather, they are all branches of Arich Anpin. Accordingly Arich Anpin cannot be considered in the same category as the other Partzufim of Atzilut since Arich Anpin is the root while the others are branches of Arich. However, when speaking of Atzilut as a whole with its root and branches, we also include Arich Anpin. Rabbi Shimon bar Yochai alludes to this mystery in his words in the Idra Zuta (288a): “Only the Lamp exists”.