"‘External feelings’ refer to physical feelings, feelings of pleasure, pain, and neither pleasure nor pain in the various parts of the body. ‘Internal feelings’ refer to the feelings of pain, pleasure, and neither pleasure nor pain in the heart. ... These things are the bosses, lording it over the heart. ... The heart is their vessel, their seat. That’s where they sit. Or you could say it’s their toilet, because that’s where they defecate. Whichever one comes along, it gets right up there on the heart. Now pain jumps up there and defecates. Now pleasure gets up there and defecates. Now a feeling of neither pleasure nor pain gets up there and defecates. They keep defecating like this, and the heart is content to let them do this, because it doesn’t have the mindfulness or discernment to shake them off and not let them defecate. This is why we have to develop a great deal of mindfulness and discernment so that we can fight them off."