Someone asked me about the more mystic teachings of Torah and I thought to share my thoughts with the wider public. I have to say that my impression has been for a long time that the best book of mysticism that I have ever seen is the Tree of Life [Eitz Haim] of Rav Isaac Luria. (The other writings of the Ari I think are better to learn after that.) After that, I think the best is the Nahar Shalom of Shalom Sharabi. [The reason I say this is that even though the Eitz Haim itself is pretty much self explicit, still there are two problems in putting it all together. One is the "Drush HaDaat" which was not included, but implies a modification of that whole system. Plus there is the whole second half of the Eitz Haim which automatically implies a sort of modification on the whole system. The only book I have ever seen that addresses these two problems is the Nahar Shalom of Rav Sharabi. [The two sidurim of the Rashash take the system of the Nahar Shalom into account.]
However I should add that I gained a lot from learning the ideas of Avraham Abulafia, Rav Moshe Haim Luzato (Ramchal), Rav Yakov Abuchatzeira, the Gra, and Rav Nahman of Breslov.
Outside of these few, the problem with mysticism is that most of it is from the Dark Side [Sitra Achra]. --The way to avoid that problem would be by taking heed of the signature of the Gra on the letter of excommunication that already drew a line between what is OK and what is not. Rav Nahman of Breslov was not under that excommunication in spite of what most people think, and hinted plenty of times to the same thing the Gra was talking about, but also ignored. The Na Nach group however based on Rav Israel Odeser seem to be a bit more aware of this issue. [Rav Oddeser was also plain and open about this issue.]
[The problem with Torah from the Sitra Achra is not just that it is wrong. but that it brings wickedness into the heart of those that study it. ]
