"Late Fragment" is a short poem written by the man himself, Raymond Carver.

Here it is in its entirety:

And did you get what
you wanted from this life, even so?
I did.
And what did you want?
To call myself beloved, to feel myself
beloved on the earth.

(Source)

It's the last poem in his last published work. He wrote it while dying of cancer, and it appears on his gravestone. But, while this poem marked the end of Carver's life, it marks the beginning of this film: the movie starts with "Late Fragment" as an epigraph.

But here's a question: is the "feeling beloved" that Carver talks about wanting in the poem any different from the kind of love that Riggan spends the movie chasing? Doesn't Riggan also want to feel himself beloved? "Late Fragment" shows us how this life goal of wanting to be remembered in a certain way can sound like a sweet sentiment or an egotistical nightmare…depending on how it's framed.