WIE: What is the ego according to Ch'an Buddhism?
Master Sheng-yen: In Ch'an Buddhism the idea of ego revolves around the idea of attachment or clinging. The ego originally does not exist. It is created as a result of attachment to the body and attachment to one's ideas or one's own viewpoint. But because both the body and the mind are impermanent and constantly changing over time, our attachments to them are always changing as well. And as these attachments change, the ego also changes. So from the perspective of Ch'an, the ego does not exist in the sense of being a permanent, unchanging entity. The ego does not exist independent of one's changing attachments to one's body and one's ideas.
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An often quoted phrase from Dogen-Zenji is: "To study Buddhism is to study the self, to study the self is to forget the self, to forget the self is to be enlightened by all beings."