from "My Brother's Book"
Sendak was already in the hospital when he saw the final layout; he was “delighted, ecstatic” with it, di Capua [his editor] remembers. It was his last look at the book. He died four days later...

At the end of a 2006 New Yorker profile, Sendak said, “When my brother Jack died, I wanted to do something extraordinary for him. Five years later, I had an idea. The poem I wrote was very dark. I hope to finish it.” 

He did finish it, and in the finishing it grew to be more than just a poem for Jack. It was a fearless and tender look at his own fate, and a farewell gift to all who loved his work.