A teacher is not a guru. Not in the spiritual sense. A Guru , in a spiritual sense, may not even say or talk even a full sentence, but in silence, awakens your shakti and may leave
Of course that is helpful only for a very advanced soul of the character of mantra maheshwar.
The rest of the people, being entirely ignorant, dwelling only on logic and thought, need constant discussions, reinforcement, reminders, books etc For them , no experiences can help. The weakness of their own mind will constantly bring them down. A Guru would have to work very hard for them
So a real spiritual Guru is very rare. Just as rare is such a disciple. They exist. They help. But as long as we need logic a Guru of that caliber even present right in front of us , will be hidden due to the impurity of our thoughts
Bhavin