My aunt Emma Andrews' 100th birthday was Friday, so I paid her a visit at her Northwest Washington home with the notion that I'd do most of the talking because you know elderly people will doze off, or at best forget who you are.

So I went to her home near 12th and Harvard streets NW, where she has lived for 51 years, and I saw this woman seated at a dining table, laughing and talking on the telephone, and I'm thinking Aunt Emma (she's my grandmother's sister on my mother's side) must be upstairs because no 100-year-old woman can be having this much fun.

But it is Aunt Emma, and -- if I'm lying, I'm flying -- she looks younger than she did last year.

Emma is so lovely, with skin so smooth that it makes Oil of Olay feel like sandpaper. Her face is strong, with bronzed cheeks. Her hair is beautiful, and although her eyes don't see too well anymore, she maintains an ageless inner vision.

"What is your secret?" I began with the standard applesauce opening for conversations with the elderly. It was just a compliment, and I really didn't expect much of an answer.

But Aunt Emma laughed heartily, showing off her teeth.

"I eat lots of vegetables," she said. As for my appeals to her vanity, she discounted that, placing a premium instead on what she thought I needed to know.

"God determines if you live a long life," she said solemnly. "But to live a good life you have to abide by the Golden Rule: 'Do unto others as you would have them do unto you.' "

The U.S. Census Bureau recently reported that the number of Americans 100 years of age and older had soared by two-thirds since 1980, because of advances in medical technology. Still, most of them live in nursing homes and hospitals and many are barely hanging on.

Aunt Emma, on the other hand, was as much in control of her faculties as I was -- and more so when it came to memory. When she recalled the time that the oldest of my two sisters and I had beaten my grandma's pig with a stick on a farm in Johnston, S.C., in 1960, I almost fell out of my chair.

No one was supposed to know about that, let alone remember it after all these years.

Aunt Emma was simply incredible, standing head and shoulders above her peers.

"She wakes up at about 5:30 each day, maneuvers herself into a wheelchair and rolls into the washroom where she dresses without much help," said her daughter, Sophia Wilson, who is 75. "Then she gets the paper and reads your column {awwright!}, if nothing else, and then the Bible. Then she gets on the telephone to check up on friends and relatives. That's how she keeps in touch with the world."

Said Johnie D. Wilson, 72, one of Emma's four sons, "As far as having her as a mother is concerned, her big thing is religion. You must go to church."

Emma Andrews is a member of the Vermont Avenue Baptist Church in Washington and served on the Deaconess Board and the church's November Fellowship Club. Board president Mary Nuttal said of her, "She is able to get along with everybody and she does whatever needs to be done to make a project grow."

Scores of friends and relatives came from across the country to pay tribute to Emma Andrews Friday night. It was noted that she grew up without electricity but lived to see man land on the moon. Grover Cleveland was the 22nd president when she was born, and here she was now receiving a letter of congratulations from President Reagan, the 40th.

Called the "Harriet Tubman" of her family, Aunt Emma had opened her home to almost anyone who needed a place to stay as black folks made that historic trek "from field to factory" and beyond.

"Without her, a lot of us wouldn't have made it," said cousin John Watkins, a lawyer in Augusta, Ga. "Her dignity, her poise, culture and perseverance rubbed off on everyone who came in contact with her."

Here was a woman whom I don't believe medical science can explain. Indeed, the only way to truly measure her life is by her own yardstick: the Golden Rule.