Conversation so far:
What kind of illness did playwright Eugene O'Neillhave?
Eugene O'Neill faced a severe Parkinsons-like tremor in his hands.
How long did playwright Eugene O'Neill suffer from Parkinsons-like tremors?
The Parkinsons-like tremor in Eugene O'Neill's hands made it impossible for him to write during the last 10 years of his life.
Is Parkinson's Disease what killed playwright Eugene O'Neill?
The examination of Eugene O'Neill's brain clearly shows that he did not have Parkinson's disease.
Was playwright Eugene O'Neill's death caused by health problems or suicide?
Eugene O'Neill suffered from a disorder called late-onset cerebellar cortical atrophy.“
What year did playwright Eugene O'Neill die?
Eugene O'Neill died in 1953.
Are there any other interesting aspects about this article on playwright Eugene O'Neill?
In Warren Beatty's 1981 film Reds, Eugene O'Neill is portrayed by Jack Nicholson, who was nominated for the Academy Award for Best Supporting Actor for his performance.

Question: What was he referring to?
Self-contained rewrite: What was playwright Eugene O'Neill referring to in his last words on his death bed?