[Advaita-l] Shankara's view on Guru without having Shatra study

[Vivek]

Hari Om,

Dear ones. I'd like to get an insight into something 

It seems that Adi Shankaracharya promoted only the idea of someone being a Guru that has learned the Shastras. 

But there have been and are Mahatmas that are in the highest state and in that state have full knowledge of all the Shastras even though they have not studied them. 

That category seems to be on the bottom of the Guru list according to Shankara. 

Some views don't agree with this. 

Could someone expand their thoughts on this?

Vivek.