This is the answer to an apparent contradiction in the teachings relating to the Primordial Kings. On the one hand we are taught that they were from the side of Malchut and were therefore lacking repair (Etz Chayim, Shaar Shevirat HaKelim ch. 8, 47a). Elsewhere, however, we find that, on the contrary, it is the rule of Malchut that brings the repair (Etz Chayim, Derushey HaNekudot ch. 3, 37b).
The proposition consists of two parts: Part 1: The beauty and delight... This explains how Malchut is the source of joy and of sadness. Part 2: Accordingly... How this relates to the Primordial Kings.