The ultimate intention behind the entire order of the Sefirot and the way they govern is to bestow complete and perfect good in the very end. It is just that in order to reach this ultimate goal it is necessary to go through the entire cycle until the end. The world must be governed with justice and the sinners punished in order that afterwards the goodness bestowed will be complete. The justice which is required prior to the end thus derives from the ultimate purpose itself – even though they seem contradictory.
Thus the nature of Arich and Zeir Anpin is that Arich Anpin is rooted in the mystery of complete beneficence, for Arich Anpin only bestows good. Yet even so, out of Arich emerges Zeir Anpin, which is rooted in the mystery of Justice, for Zeir Anpin is born out of the intrinsic purpose of Arich Anpin itself.