The arising， abiding， changing and extinction of all existences. Also called the four aspects （四相） of arising， abiding...etc. Also called 'four characteristics'， 'four conditioned aspects.' For the Sarva^stiva^dins 有部， these aspects of arising， abiding， changing and ceasing are said to be the nature of real existence. For the Sautra^ntikas 经量部 and so forth， these are not considered to be real， but four provisionally established characteristics. Yoga^ca^ra theory 瑜伽行派 is also opposed to the Sarva^stiva^din interpretation.