Excerpt from the Sutra of Perfect Enlightenment

Original text:善男子。云何我相。谓诸众生心所证者。善男子。譬如有人。百骸调适。忽忘我身。四支弦缓。摄养乖方。微加针艾。则知有我。是故证取。方现我体。善男子。其心乃至。证于如来。毕竟了知。清净涅槃。皆是我相。

Explanation: The Buddha said: "Sons of goodness, what is the mark of self? What are the manifestations and characteristics of the mark of self? The mark of self is that aspect which the consciousness mind of sentient beings can realize and can know—the aspect of the knower. Sons of goodness, suppose there is a person whose entire body—joints, muscles, sinews, and vessels—feels completely comfortable, without the slightest disharmony or discomfort. As a result, this person forgets the existence of the physical body, and there is no sensation of the body in the mind; the four limbs are completely relaxed, and even the location of the body is unknown—there is no information or thought about the body at all. At this moment, if a fine needle is gently pricked into his body, he immediately becomes aware of the existence of his body, and thus he realizes the self, and the concept of 'my body' appears. Sons of goodness, even when the mind realizes the Tathāgata and can ultimately and thoroughly know the pure nirvāṇa, all of this is the mark of self."

This passage spoken by the Buddha shows that the mark of self is very subtle. The coarse mark of self can be realized and eliminated by arhats, but the extremely subtle mark of self can only be realized and eliminated when one has cultivated to the stage of a bhūmi bodhisattva. Here, the mark of self refers to sentient beings' extremely subtle knowing nature regarding themselves and all dharmas. As long as there is a single knowing—no matter what is known, no matter how subtle what is known is, no matter how fine the knowing is—it is the mark of self; without a self, there is no knowing. To recognize and accept this knowing nature is the self-view (ātma-dṛṣṭi); to grasp and cling to this knowing nature is self-grasping, which may also be called dharma-grasping; dharma-grasping is subtle self-grasping. Having recognized and accepted this knowing nature is ignorance; there will be karmic formations, and there will be transformational birth-and-death, and one cannot attain ultimate nirvāṇa.

If a sentient being says, "I have attained the fruit," and recognizes and grasps the mind aspect that attains the fruit—this realizing nature—that is the mark of self, that is self-view. If someone says, "I am enlightened," and recognizes and grasps this mind aspect capable of enlightenment, that is the mind of self, that is self-view. If a sentient being believes "I am good, I am the best; he is bad, he is the worst," then there is the mark of self, which is self-view; by means of this self-view, one will create the karma of birth and death, and there will be segmented birth-and-death and transformational birth-and-death, and one cannot attain liberation and nirvāṇa. If someone believes himself to be superior to others and thus constantly elevates himself while belittling others, this is a severe mark of self, a coarse mark of self; the karma of birth and death is heavy, and the three evil destinies cannot be avoided. If someone goes to great lengths to conceal his own shortcomings and weaknesses, that is a severe mark of self; if someone goes to great lengths to expose and attack others, that is likewise a severe mark of self. Both are coarse and heavy marks of self; with heavy self-view, the three evil destinies cannot be avoided.

All bodily formations, verbal formations, and mental formations are the mark of self. Without recognizing and grasping them, there is no self-view; having recognized and grasped them, there is self-view and self-grasping. The behavior of shielding one's own faults and of fighting and contending is the mark of self; the various expressions on the face are the mark of self—for example, embarrassment, blushing, awkwardness, shyness, joy, anger, and hostility all contain the mark of self. All evil and unwholesome actions contain the mark of self, and the wholesome actions of most sentient beings also contain the mark of self. The wholesome actions of the noble ones are natural and spontaneous, arising effortlessly, without the mark of self; in all of the Buddha's bodily, verbal, and mental actions, there is no mark of self.