That which rises in this body as 'I' is the mind. If one enquires 'In which place in the body does the thought 'I' rise first?', it will be known to be in the heart [spiritual heart is 'two digits to the right from the centre of the chest']. Even if one incessantly thinks 'I', 'I', it will lead to that place (Self)'.
Nan Yar = Who am I?