PHOENIX, ARIZ. -- Her name is Helen, and she is a lovely woman with white hair and clear, piercing blue eyes that have a way of settling on you with a look of expectation -- like she knows you are about to say or do something worthwhile. She looks smaller than she really is, and she is much tougher than she looks, and surely she is as tough as or tougher than the minister says she is.

At the church services Sunday, he described her as the toughest woman he knows, but he is young and he hasn't been here long enough to remember what it was like for her 25 years ago when she arrived here from New York, alone and lonely, to join the man she had married, the man who had fathered her three sons.

They came here in the hope that the Arizona sun would arrest her husband's rheumatoid arthritis, the disease that was already crippling a once-strong man. She left a job and the life she loved in New York for a life she knew would be harsh, and which turned out to be harsher than she could have ever known. She came here out of hope and, of course, love, and she came here out of loyalty. There have always been rules in Helen's life, and she has lived by them. This man was her husband and she would go with him, and in the years when the pain and the cortisone made him at times unrecognizable, she was here.

"It's not much to look at," said her youngest son when he drove by the rest home late last week, "but now you know what it looks like when she talks about it." She talks about the religious order that nursed her husband, a non-Catholic, and she tells you "they were so good to him." She does not talk about herself. She doesn't tell you how much she did and how hard it was at times for her. Her youngest son can tell you, though, and so can his wife. They, too, were here in Phoenix, for the last years, working here and able to help.

There was a long time when the daughter-in-law went to the home every day during her lunch hour to feed him or to help him smoke a cigarette or two when he could no longer move his hands well enough to smoke alone. The Little Sisters of the Poor did not have the human resources to care for someone who could not feed himself, so the daughter-in-law said she would do it. "I did it because it was necessary and also because I'd learned to love him. To respect him. I'd admired him so very much because with all of his pain and suffering he never lost his sense of humor. I'd go in there and his eyes would light up. He'd have a story to tell me. Impatient he did get at times with his disabilities, but he never lost his sense of humor."

Nor did Helen. "She always stayed cheerful," said the daughter-in-law. "She was not one to unload her troubles on others. People who came into the dress shop had no idea she had an invalid husband."

Helen's husband, whom she calls Jack, and the father of her sons, whom she calls Pop or Dad when she talks of him to them, died in 1971. Two of her sons, including one who remains in New York and the son who lives in Phoenix, were here for his funeral. It was the closest thing to a family gathering that has occurred in her family since she left New York in the middle '50s and came west.

And yet her family, separated by the distance between the East Coast and Arizona, separated by divorces and remarriages that have occurred in the homes of two of her sons, has remained together. This is in part, at least, because of her letters. Helen has continued to write letters in an age of telephones, to write the trivia of family life in a neat script on nice stationery in an age that has proclaimed the disappearance of the family.The sons and daughters-in-law who live on the East Coast know of each other's activities and they know what the grandchildren are doing because they read it in Helen's letters. She has kept in touch with the original daughters-in-law and they with her.

It is through these letters and the phone calls that were made in recent months that an event occurred here last weekend. It was Helen's 75th birthday, a fact duly noted in the Sunday service at the University Baptist Church of Phoenix when the minister asked her to rise. Up and down the pew were sons, their wives and grandchildren, gathered here from New York and California, where some of the grandchildren are living now. This weekend was the first time since 1954 that her three sons have been together and that means it's the first time they've been together with her in over 25 years.

For once she got emotional. Saturday night she gathered her sons about her for pictures and they sat with her on the sofa of the home she shares with her second husband, a retired minister, and she told them that having them together fulfills her wish. Then she spoke about the surgery she faces soon. It is dangerous, and she knows it.

"This may be the last time we'll all be together," she said, and then tears gathered in those clear blue eyes for a moment and she looked down. Next to her, three grown men, men who have survived wars and marital breakups and economic hardships, and many of the joys and sorrows that befall families in these times, men who would easily have put their arms around their own distraught wives and daughters and comforted them, sat not quite knowing what to do.

They had never seen their mother overwhelmed before.