Part 12 · Chapter 43

And it is now found that of the aspect of ZA that is in the eight Sefirot, from Keter to Netzah, all were completely clarified, and nothing of them remained unclarified. Therefore all that remains of those eight Sefirot is called complete dross, in which there is nothing that can rise and be clarified to become fit for the portion of ZON of Atzilut; therefore this dross goes out in the secret of the blood of birth.