The answer is that during the six thousand years of the world’s existence, the world is like one Partzuf divided into three parts: the head, the body, and the end. These three parts parallel [the units of three Sefirot:] ḤaBaD [Ḥokhma, Bina, Daat], ḤaGaT [Ḥesed, Gevura, Tiferet], and NeHiY [Netzaḥ, Hod, Yesod]. The Sages state [that those six thousand years] are two thousand years of chaos, two thousand years of Torah, and two thousand years of the Messiah (Sanhedrin 97a). This means that during the first two thousand years, [the world will be] like a head without a body, [for the head contains] only the lights of Nefesh.