What is feeling?

The so-called world is nothing more than a feeling. Different states of mind give rise to different feelings, and different people have different feelings. So what are these feelings? They are nothing at all—mere illusions and transformations. Then what should be done? Change feelings that are not real and not reasonable into feelings that are real and reasonable, and one will return to truth, return to awakened nature, return to the One True, return to nirvāṇa, return to tranquility.