Question: What is the nature of the mind?
Bhagavan: What is called ‘mind’ is a wondrous power residing in the Self. It causes all thoughts to arise. Apart from thoughts, there is no such thing as mind. Therefore, thought is the nature of mind.
When one persistently inquires into the nature of the mind, the mind will end leaving the Self (as the residue). What is referred to as the Self is the Atman. The mind always exists only in dependence on something gross; it cannot stay alone. It is the mind that is called the subtle body or the soul (jiva).
Bhagavan Sri Ramana Maharshi