The Most Difficult And The Easiest Science: Kabbalah
It is known that the Creator created only the will to enjoy. This desire, "the body," develops and produces a mind or "head" within itself to help it attain what it desires. The entire mind or "head" works for the will to enjoy, the "body." If the desire or "body" needs something, then the mind or "head" begins acting in order to attain the desired thing. If the body does not need anything, then it is as if there is no mind or "head." Thus, the presence of the mind or "head" is defined by the size and level of desire.
When we study Talmud Eser Sefirot trying to understand it mentally, then we are trying to understand something that does not yet exist in our desire. That is because Talmud Eser Sefirot talks only about actions of bestowal, which are above our egoistic desires. That is why it is impossible to understand the meaning of spiritual actions; the head (the mind) can only think on the level of the bodily desires. It can only perceive whatever the desire understands. And if something is absent in the desire, then it is not present in the head as well. That is how material nature is built as well as the spiritual one. The body and head relate to one "Partzuf" or state.
Therefore, if you see a person who is very proficient at knowing the structure of the Upper Worlds, then either he is already in the spiritual world or he is studying it purely mechanically, not for the sake of correcting the desire. He may study and know a lot of theory, like the "Kabbalists" that Baal HaSulam once met in Jerusalem.
However, it is impossible for a person who came to correct his desire to understand the structure of the Upper World until the phenomenon he reads about in the book start to be revealed in his desire at least a little bit. With this initial revelation he will already have the ability to remember something, to talk about it, and to imagine it in some way.
Therefore, it is not a bad thing if a person studies for a long time and still does not know anything. In fact, this is a sign that he is advancing correctly. His desire and mind are connected together, and his mind works only to the degree he corrected his desire. This is the healthiest form of development.
-from the 3rd part of the Daily Kabbalah Lesson 8/2/10, Talmud Eser Sefirot