As any other science, Kabbalah is based solely on experiment. Look at a little human being, how he grows—this is how we used to develop in the past.
Over the course of millennia, we continuously summarized all of our observations and gradually turned them into the sciences. However, all of them are based solely on experiment, and nothing more. These experiments comprise the foundation of all sciences.
If something is not tested experimentally, it is not a science. It could be a product of your imagination, and another person could come up with something else. Only strictly recurrent data, results of experiments, can be turned into a science.
Suppose today I’m in my lab and I study a certain property or phenomenon. Consequently, I write an article for a scientific journal about the behavior of the phenomenon under question. Later, the results presented in the article are tested in other laboratories and places, and scientists write their feedback. Science is made up of all these elements.
This is how it was over the course of millennia. But today, we do not develop the science of Kabbalah, but rather apply it.
As of today, the wisdom of Kabbalah is already explicated, set out on paper. We have nothing to add, except for the materials that we write to help ourselves and people like us. That is, suppose there is certain upper physics, and then it is written out for students, for schoolchildren, for laymen, or for various practical applications. The same applies to Kabbalah.
Today we read The Book of Zohar, the works of the ARI, which are set forth and commented for us in the books of Baal HaSulam. Essentially, we have nothing to add to this. There are also articles and letters, meaning other material which we received from Baal HaSulam. Practically, this is it.
Beside this, we can only write about what we observe, see, in ourselves so as to assist other people who advance together with us or will follow us. That is, we do not develop the science, but adapt it for those who will come to it.
From Lesson 3 Berlin Convention 1/28/2011