Brooke Astor always prided herself on good manners, and in her later years, decried the downward trajectory of American culture. Men no longer tipped their hats at women, she complained, and folks were introduced to one another by their first names. “We might as well all be called Fido,” she wrote in a June 1999 essay for Vanity Fair. Given her attitude, Astor probably would be shocked if she knew the mountain of intensely personal details that have been exposed during the ongoing trial of her son, Anthony Marshall — but the courtroom drama is also providing a primer in good behavior.

“She was always charming, proper, humorous, decisive and correct,” testified Carnegie Corp. head Vartan Gregorian on Monday. Like other witnesses, he remembered reams of thank-you notes from Astor, as well as quips to suit any occasion and offered her general rules of etiquette: “Once she gave, she never took back,” he said, and “her word was her bond.” And never, ever, was business discussion allowed at her many cocktail parties and teas. “It was considered déclassé and unsociable.”

This story first appeared in the May 19, 2009 issue of WWD. Subscribe Today.

However, as her hearing and mental condition weakened, Astor’s exquisite manners suffered too — sometimes revealing her often amusing internal monologue.

“Who is that?” Astor loudly asked Gregorian when introduced to Catherine Zeta-Jones. “She is wearing the wrong dress for the occasion,” Astor announced. Zeta-Jones pretended not to hear.

Camilla Parker-Bowles took a similar tack when Astor toasted her at a party in her honor. “Mrs. Keppel would have been proud of you,” Astor said, a reference to Parker-Bowles’ great-grandmother, Alice Keppel, the rumored mistress of King Edward VII.

“Camilla feigned politeness though she had just been told that for generations her family provided mistresses [to the royal family],” said Gregorian.

And when accepting a Carnegie Medal of Philanthropy in front of an audience that included George Soros, Ted Turner, David Rockefeller, Tom Brokaw and Lee Annenberg, a disoriented Astor discussed her disastrous first marriage. “When I was young, I married a perfectly terrible man. They were not what you call interesting people, but they had a lot of money,” she said in a video of the speech that was shown Monday. But despite rambling, she still had some valuable advice for the audience. “You can’t expect to have it good all the time,” she said, before philosophizing on civic duties. “Don’t hurt [people] — always try to help them. If they’re absolutely nuts and stupid, stay away from them.” One has to admit, even then, she had a point.