Forgetting oneself is opening oneself - Dōgen

"Delusions mean our individuality, our limitations as individuals, and also egocentricity. We cannot see the universe from the viewpoints of other people; we can see things only from "my" point of view. I cannot see from your point of view. Even though I think I can understand it, I really cannot see it, because it is not reality for me."

Furthermore, form and substance are like dew on a blade of grass, and fleeting life is as a flash of lightning, instantly emptied and immediately lost.

You should understand that birth-and-death is itself nirvana. Nirvana is not realized outside of birth-and death.