Is the Mind (Citta) the Self? If not, what is it?

It's been discussed in all perspectives that the Buddha was teaching about not-Self (Anatta) in this forum. However, it taught that one should empty the Mind (Citta) to realize Anatta, or Sunyata, in Dhyana (Jhana). If this mind is already not-Self, why it needs to be emptied and what is to be emptied? If this mind is also not-Self, how does it have the autonomy/independence to realize/discern Emptiness? If this mind is Self, how can it realize not-Self? If this mind is not-Self, who controls/owns the Five Aggregations and intellect? Who/what is this mind?