Answer: Working in three lines is the complete mutual connection between your inclinations.
The left line is the egoistic desire to receive, to enjoy. By ascending above it, a person restricts its use.
The middle line is the combination of the right and left lines inside you. In the right combination, you can use your egoism only to the extent that it is aimed at bestowal.
Question: What does it mean to acquire the letters of the spiritual work?
Answer: It means to acquire a collection of correct relationships between the friends in the group.
From the Kabbalah Lesson in Russian 12/18/16