Part 1: The essence of the Chariot consists of these names of AV... The Chariot is the overall bond of the entire governmental order, which consists of four levels, which are the four Chayot. Their essential function is bound up with these four names of AV, which are the mystery of Abraham, Isaac, Jacob and David, as explained in the teachings of the ARI (Pri Etz Chayim, Rosh HaShanah ch. 7).
At first sight this may appear problematic, for if these are the number of lights that descended at the time of the breaking of the vessels, as appears from the discourse on the 288 Sparks (Etz Chayim, Shaar RP”H ch. 2), what connection do the four legs of the throne – Abraham, Isaac, Jacob and David – have with this? However, the main point to grasp is that the root of these four names of AV lies in the mystery of the Chariot, as stated, but that from here various aspects of them descended lower, as will be explained below.