This darkness led me to write a commentary on the works of Rabbi Isaac Luria, the Ari z”l, and later on the holy Zohar. I was able to remove this fear by explaining and demonstrating clearly that these parables are not speaking of something physical, but of something spiritual, something more abstract than anything that can be imagined in the physical world, something above place and time. Those who read [those commentaries] will realize that they can enable every Jew to study the Zohar and be warmed by its holy light.
Isaac and the Patriarchs
Baal HaSulam's Introduction to Zohar 58:2