Another book that is very illuminating is "My Stroke of Insight" by Jill Bolte Taylor. Reading the brain stroke description can give non-experiential understand

Another book that is very illuminating is "My Stroke of Insight" by Jill Bolte Taylor. Reading the brain stroke description can give non-experiential understanding of various Zen koans, including the non-verbal one where Buddha simply holds up a flower and it becomes entirely understandable to Mahakasyapa. It also points to the natural tendency of human beings to attribute profoundness or spirituality to various forms of brain malfunction. The author does it in the later chapters of the book.