A student who wants to acquire wisdom from a teacher has to receive it in the right form, in the dressing of the upper acting mind. The same thing happens in an ordinary school to a certain extent, since each of us is born as raw material from which a certain form is later molded and is accordingly filled with different knowledge.
We always receive from others both the essence of the knowledge and the external form it is dressed in. This is how it happens in the upper spiritual roots and in our world. So it is very important from whom you learn. The knowledge is conveyed in the same way through books without the live contact with the author. Even in external corporeal sciences we always acquire knowledge as if “the Direct Light is dressed in the Returning Light.”
So it is especially true when speaking about the wisdom of Kabbalah. Here in order to convey information, there has to be a connection that is called “mouth to mouth,” a connection of “spirit in spirit,” which means that the Returning Light has to be compatible to a certain extent in giving and receiving. Of course, they are on different levels, but there is a certain resemblance between them, and so the lower can receive an illumination from the upper one.
These are intentional actions that take place in one’s understanding and recognition when there is a spiritual revelation.
If in external science we are concerned with the inner content, the knowledge itself, in the wisdom of Kabbalah we are concerned about the external form, the adhesion, and then in it, to the extent of the adhesion, we receive the Internal Light, and not in any other way.
From the 1st part of the Daily Kabbalah Lesson 9/4/12, Lesson About the Greatness of the Rav