Each one of the five levels within the fourth level enclothed the corresponding level in the ten sefirot that are encompassed in the supernal light: The root level aspect of the fourth level enclothed the light of Keter of the ten sefirot. The first level aspect within the fourth level enclothed the light of Ḥokhma of the ten sefirot, the second level aspect within the fourth level enclothed the light of Bina, the third level aspect within it enclothed the light of Tiferet, and the fourth level aspect within the fourth level itself enclothed the light of Malkhut.
Therefore, now too, after the first constriction (tzimtzum), when the fourth level has been disqualified from being a receiving vessel any longer, the five levels of opacity (ovyut) within it are still called by the name of the five sefirot, Keter, Ḥokhma, Bina, Tiferet, and Malkhut.