Shri Shankara Acharya’s Vakyavritti Verse 50
“When the conviction of the truth of the holy dictum is attained by the grace of the teacher, and the holy Shruti, then the aspirant is wholly freed from the limitations of sansara and its cause, nescience.”
The greatest prominence is given in the holy teachings to the grace of the teacher of Shruti.
A teacher of secular knowledge or theosophical mysteries or Hatha Yoga practices is not considered a Guru.
A real Guru must be a teacher of the holy Shruti, and the essence of the Shruti is contained in the four great dicta,‘I am Brahman’ and so forth.
The grace of God flows from the teacher himself; just as a room in winter is heated by a radiator which has first been heated itself, so the grace of God shines forth through the Self-realized Mahatma who teaches the meaning of holy Shruti confirmed by his own experience.
The egoity of the disciple, which is the chief barrier between him and the ever-shining splendour of God-head in his Atman, is thinned out by submission and surrender to the teacher.
God is revealed as the Self.