All in the mind/brain?!

If you don't really know who you are you may become dependent on someone telling you who you are. It's not wrong but it's not right either is it?

A strong 'ego' will be strongly opinionated and a weak ego will be ill defined and looking for some certainty. This is where the Guru/teacher comes in.

If the Guru teacher is 'clean, clear and authentic then some clean, clear and authentic teaching may occur, leading rather rapidly to some (usually) intense lessons in enlightenment teachings.
If on the other hand the teacher/Guru is unclear and in denial then the teaching may meander around forever. The weak ego has no 'real' way of knowing whether a teacher is clear or unclear. On the other hand the strongly opinionated egoic teacher/Guru will have a vested interest in keeping many 'ill defined' ego's wandering around in the dark. This has to happen otherwise the 'egoic' teacher has no role to play and would therefore not exist.

What can we do?
How can we know?
Open the eyes.
Listen very closely to what is being taught and spoken.
If it doesn't make sense it is probably bullshit - Go elsewhere.
The best place to go is within...........