The Book of Zohar was written in the second century by ten Kabbalists who gathered together in a cave, wrote it over a long period, and then hid it. The Book was found in the eleventh century, but it was not truly revealed until the twentieth century. Since that time it has become suitable for understanding and use by Kabbalists. And before that even Kabbalists could not understand it.
The great Kabbalist of the 20th century, Yehuda Ashlag (Baal HaSulam), wrote the Sulam Commentary on The Book of Zohar, and it became a working book for us. Why? If we gather among ourselves in dozens, as did those who wrote The Book of Zohar, trying to unite with each other in order to reveal the upper world and describe it, we act in the same way they did, and then we begin to understand what they wrote.
In our time The Book of Zohar becomes especially relevant for us, since now souls who are capable and ready for such comprehension have descended into our world. And although this book has passed through many generations, it is in our generation that it has really become a tool for comprehending the true universe and managing our own destiny.
From KabTV’s “Conversation about The Book of Zohar”