The brahmanista master sees the truth, so it's much easier for the enlightened master to transmit at knowledge to the student. It's like a professor who has understood what the text books are teaching and then teaches it under one who hass not particularly clear. If you don't see, you may be able to help the student, but not very effectively.
Swami Sarvapriyananda teaches the Katha Upanishad, which is one of the most popular Upanishads. The scripture concerns the story of a young man who goes to the house of death to find out what happens after death. The reply describes the nature of reality and the meaning of life.