Well, when we are going through a certain phase in our life, where we have to make a decision but we are unsure of what is correct & what is wrong; normally, we have two directions/instructions to follow, one from our brain and the other from our heart. So, the question arises which one is supreme & correct guide, and why?

Mann -> Mind &
Budhdhi -> Brain

I would like to cite a simple example here:

You go for shopping right?

* Mann -> buy this buy that
* Budhdhi -> before buying check your budget
* Mann -> No worries I'll use Credit Card
* Budhdhi -> Who will pay Credit Card bills?

So, a simple decision making process in a way shows which one is a better guide. Maybe that's the reason brain (budhdhi) is placed above heart (mann) in a human body!

Some say listen to your Atman, but question is how is that message passed on to the person, through Mann or Budhdhi or some other means?