From Who Am I?
The Teachings of Sri Ramana Maharshi
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.
Apart from thoughts, there is no independent entity called the world. In deep sleep there are no thoughts, and there is no world. In the states of waking and dream, there are thoughts, and there is a world also.