The Zohar provided the mystical dimension that must originally have been present in Judaism. The consensus among today's scholars is that some parts of it are quite old, going back to just before and just after the destruction of the Second Temple. Quite a few quotations and prayers from the Zohar found their way into the mainstream liturgy, though most were removed after the failed messianism of Sabbatai Zevi caused the Zohar to fall under suspicion. It did fill a need, and therefore was very popular among the Jews.
Interestingly, the Christians found the Zohar interesting too, for various reasons including a messianism that some thought could serve their purposes. Very few Christians could read Aramaic and Hebrew, but in 1677-8, Knorr von Rosenroth published his Kabbalah Denudata, in Latin. This was translated into English in 1887 by S. L. Macgregor Mathers, and the race to mine the treasures of the Zohar was on.
Mathers, A. E. Waite, and others (W. B. Yeats was involved, too) founded the Golden Dawn. They had a great interest in everything Kabbalistic, especially the Tree of Life and the Sephiroth. I have seen a color diagram of the Etz Chayim from one of Yeats' own notebooks. Uncountable other Western occultists were also interested (and many still are).
The original Golden Dawn did not last forever, and one of its members, Israel Regardie, decided to publish its rituals, considering that preservation was more important than secrecy. This gave rise to whole new generations of Kabbalah-enthusiasts.
As an aside, I have Regardie's boyhood Pentateuch, which he kept with him all his life. It does not contain any secret messages or anything like that, but it does have his bookplate and a prize-award plate from his Hebrew teacher. (See below.)
Text and images Copyright © 2020 by Donald C. Traxler aka Donald Jacobson Traxler.
