Adam LeGrant answered the phone and said that, contrary to the arrangements that had been made, his mother was not going to come on the line to talk.

So it fell to him to deliver the news: She has retired. He said this in the past tense — not “she is going to retire,” but “she has retired.”

His mother is Barbara Cook, of the magical voice.

“She has retired” — three words that a fan feared were coming but did not want to hear, because they foreclose on the promise of more. Her fans long to marvel yet again at how she always manages to discover something different and arresting in a song they thought they knew, something unexpected and raw and authentic.

Ms. Cook is 89 now. She defied so much for so long: depression, alcoholism, age. Mr. LeGrant said, on the phone and over lunch a couple of days later, that she had decided to put out the word about retirement. “The public hasn’t seen her in months,” he said, “and somebody would go ‘Oh, my God,’ and it would be on Page Six.”