"Money is like manure—it should be spread around." Philanthropist-author Brooke Astor is the first to admit she borrowed the line from literary superior Thornton Wilder, but no one writes a more eloquent checkbook.

As president of the Vincent Astor Foundation, which her third husband established and left in her stewardship when he died in 1959, Brooke judiciously parcels out $9 million a year in grants to projects within New York City's five boroughs. "Vincent left certain guidelines," she says, "but it was my idea to spend money only in New York. The original Astor fortune was made here [in the fur trade and then real estate], and five generations of the family contributed to the life of the city. Also, New York is such a feast, such a smorgasbord of people."

Her favorite causes are little ones like the Bronx's Knickerbocker Drum and Bugle Corps, which bought instruments and uniforms with $2,500 of Astor money, or the Animal Medical Center program, which provides care for the pets of poor people over 65. "My men trustees say, 'Oh, you always give to such picayune things,' " she admits. "Well, I think women are more oriented toward people than men. It isn't always the big gifts that give one so much pleasure."

Yet she can also think big and philosophically. Thanks to a $2.9 million Astor grant, the Metropolitan Museum of Art will open its re-creation of a Ming Dynasty Chinese garden this fall. Three years ago Brooke publicly objected to President Carter's proposed high-rise housing for the arson-razed South Bronx, and the foundation pumped $85,000 into plans for an industrial park surrounded by low-rise housing. "New housing without jobs," she wrote in last year's foundation annual report, "is like a plate without food."

Clearly, Brooke has never needed a ghost writer. She published the first volume of her memoirs, Patchwork Child, in 1962, and has just updated it with the charming Footprints (Doubleday, $13.95). The volume was written, she says, "by the pool, in airports, never at a desk," and is intended to show her 18-year-old godchild, Mary Armour Reid, "what a young girl starting out can do, and what happens to her. I didn't want to be a name-dropper," Brooke adds, but there was no way she could ignore all those encounters with Maugham, Mussolini, et al.

Volume One of her cautionary bio began probably 77 years ago (Brooke fudges that one fact). The daughter of Maj. General John Russell, a former Marine Corps commandant, and his wife, Mabel Howard, Brooke had a global childhood, learning to speak Chinese before she was 10. Her mother thought "a good marriage was a rich one," so at 16 Brooke wed wealthy J. Dryden Kuser, whom she met at a Princeton prom. The marriage was a disaster, ending in divorce after eight years, but out of it came her only son, Tony, 56, a onetime ambassador to Kenya, with whom Brooke remains close. Then followed a 20-year "perfect" match with stockbroker Charles "Buddie" Marshall, who died of a heart attack in 1952 before her eyes.

Brooke was still in mourning when she met Vincent. He was the eldest son of Titanic victim John Jacob Astor 4th and Ava Lowie Willing (later Lady Ribblesdale), who at Vincent's birth had the streets around her Fifth Avenue mansion covered with straw because the clatter of carriages gave her a headache. Vincent, twice married himself, was a difficult man but a relentless beau. Brooke had become an editor at House and Garden and felt herself to be "what is now called a liberated woman." But Vincent's ardent output of five love letters a day ultimately won her.

Since Vincent trusted virtually no one, the Astors spent most of their time alone at home, talking together about his holdings, which included Newsweek, the St. Regis Hotel and the United States Line. Brooke made what turned out to be the last five and a half years of his life probably his most serene and loving. Before leaving her a personal fortune of $61.5 million as well as the foundation, now worth $50 million, he told her, "You are going to have a hell of a lot of fun running it, Pookie." He was right. Heeding John D. Rockefeller III's advice to "control the money and the giving," she personally interviews every grant applicant before giving final approval—and not in an opulent office, but in the area where the money is needed. Though always elegantly dressed ("If I'm not wearing my jewelry, people feel I'm talking down to them"), she's not above tightening a leaking fire hydrant with a white-gloved hand. David Rockefeller says, "She is always ready for adventure and the unknown."

"I go out every night Monday through Thursday," notes Brooke, who so hates wasted time that she works on her T'ai Chi while standing in receiving lines. She shuns meat and caffeine and on Fridays hies herself to the 68-acre Astor estate in Briarcliff Manor, N.Y. There she takes long walks with her two dogs and sees few visitors. "I need to be alone sometimes, otherwise I really couldn't do what I do. After all," she sighs, "I'm a thousand years old."