Answer: The Book of Zohar is the main book in Kabbalah. We study it every day. I have just finished going over The Zohar in order to simplify its language and replace all of the Aramaic words. We are now translating this book into other languages and soon it will be published.
This book explains the laws by which the spiritual, global world operates. The difference between the spiritual world and the material world is not that spirituality is somewhere up in the sky, beyond all the galaxies. The spiritual world is right here, in the same place, but we do not feel it because it works at a different frequency, so to say.
We are looking at the world through our egoistic senses where each person perceives only what is beneficial to himself. But if we change our senses and attitude to the world and desire to see it as being single, great, and one whole, then we will see the world as an integral system of forces right here and now.
This is the world that The Book of Zohar tells us about. However, this book is written in a way that takes the reader and without him even noticing, leads him into the sensation of the new world. That is why it is such a powerful and unusual book. The Zohar works through our mind and feelings, influencing us from all sides.
From my lecture in Paris on 2/1/11