"There are, O monks, these three feelings: pleasant, painful and neither-painful-nor-pleasant. Pleasant feelings should be known as painful, painful feelings should be known as a thorn, and neither-painful-nor-pleasant feelings should be known as impermanent. If a monk has known the feelings in such a way, it is said of him that he has the right outlook. He has cut off craving, severed the fetters (to existence) and, through the full penetration of conceit, he has made an end of suffering."

Who sees the pain in happiness and views the painful feeling as a thorn,
perceives the transience in neutral feeling which is peaceful — 
right outlook, truly, has such a monk who fully understands these feelings;
And having penetrated them, he will be taint-free in this very life.
Mature in knowledge, firm in Dhamma's ways,
when once his life-span ends, his body breaks,
all measure and concept he has transcended.