The External as Impermanent

“Bhikkhus, forms are impermanent. What is impermanent is suffering. What is suffering is nonself. What is nonself should be seen as it really is with correct wisdom thus: ‘This is not mine, this I am not, this is not my self.’
“Sounds … Odours … Tastes … Tactile objects … Mental phenomena are impermanent. What is impermanent is suffering. What is suffering is nonself. What is nonself should be seen as it really is with correct wisdom thus: ‘This is not mine, this I am not, this is not my self.’
“Seeing thus, bhikkhus, the instructed noble disciple experiences revulsion towards forms, revulsion towards sounds, revulsion towards odours, revulsion towards tastes, revulsion towards tactile objects, revulsion towards mental phenomena. Experiencing revulsion, he becomes dispassionate. Through dispassion his mind is liberated. When it is liberated there comes the knowledge: ‘It’s liberated.’ He understands: ‘Destroyed is birth, the holy life has been lived, what had to be done has been done, there is no more for this state of being.’”