Moreover, Sariputra, I have realized Bodhi to be without entering orexiting. What do the two dharmas of entering and exiting mean?Sariputra, the mentioned entering means attachment to all dharmasand the exiting means non-attachment to all dharmas. Tathagataclearly perceives Dharma-nature of Equality to be without enteringor exiting.
The Maharatnakuta Sutra, Vol. 39
Being circulating in three-realms (tridhatus), the embryo-enteringconsciousness always keeps its essential nature of theintrinsic-mind unchanged since eons without a beginning. Thisessential nature never changes despite any cultivation or practice.However, the gross and the subtle level mind-consciousness existingin three-realms always change. For example, beginning with ignoranceat the time of birth, followed by learning during a whole lifetime,a person becomes smarter with much more mundane wisdom beforepassing away. Starting from no idea of good and evil when taking thebirth, through meeting various chances, one may become a greatvirtuous person or a deadly wicked person. Therefore, they alwayskeep changing. Moreover, all the five aggregates (skandhas) withchangeable nature will be extinct and become nothingness when oneenters the remainderless-nirvana. How can we say that they havenever changed and are without variation? How can we say that theyare without arising or ceasing? However, since eons without abeginning until the moment an arhat entering theremainderless-nirvana, or even through asamkya eons after an arhathad entered the remainderless-nirvana, the embryo-enteringconsciousness in the remainderless-nirvana still keeps its intrinsicnature to be dwelling nowhere and never changes.
The Correct Meanings of the Agama Sutras, Vol. 5