Answer: The group must learn the method of correction on the spiritual path from the teacher, but realize it in itself. The connection between the friends has to provide everyone with such a power, with such a foundation, that they will also be ready to hold themselves in their place without the teacher. They need the teacher only to be able to advance constantly in the right direction.
But on the level that has already been attained, the group has to be already be in such mutual connection that it creates a stable base so that they don’t need anyone. In the connection between them, they discover the Creator, and in this way they advance.
From the 1st part of the Daily Kabbalah Lesson 2/27/14, Topic of Lesson: “Teacher”