The same is true of each individual Partzuf. Regarding the vessels of ḤaBaD and ḤaGaT, which symbolically reach until the chest, the lights are covered. They only begin to illuminate the revealed Ḥesed, i.e., the revelation of the illumination of the supernal Ḥokhma, from the chest and down – that is, regarding his vessels of NaHYM. For this reason, prior to the revelation of the vessels of NaHYM in the Partzuf of the world, namely in the last two thousand [of the world’s six thousand] years, the wisdom of the Zohar in general and the wisdom of Kabbala in particular was hidden [lit. covered] in the world.
At the time of the Ari z”l, when the time was approaching for the perfecting of the vessels from the chest down, the illumination of the upper Ḥokhma was revealed in the world through the soul of the divine Rabbi Isaac Luria, who was able to receive that great light. Hence, he revealed the core principles of the Zohar and the wisdom of Kabbala, setting aside all of the earlier sages.