A PASSING STRANGER MIGHT HAVE Assumed the occasion was joyous, for the music coming from Phillips Memorial Baptist Church in Cranston, R.I., on that Monday evening was Ruthie and Verena Cady's favorite song. Inside, mothers holding toddlers hummed along with Raffi's bouncy "All I Really Need."

"Inhale Ruthie and Verena's spirit," the girls' father, Peter Cady, told the hundreds of friends and relatives assembled, "and exhale any sorrow you may feel at their passing."

It was an exceptional memorial service, perfectly suited to the two small. remarkable souls it honored. Born seven years ago joined from sternum to waist, the Cady girls were what modern medicine calls conjoined twins. Although they shared a heart and part of their intestines and could not be separated, they wasted no time mourning their lot. Doctors initially predicted the girls would die within a year; instead they flourished. Ruthie and Verena learned to walk, then to ride a specially designed tricycle, to dance and to roller-skate. "They were always smiling," says Peter, 35.

Even the onset of heart and respiratory problems, which ultimately took their lives on July 19, did little to dim their spirits. "They were using oxygen tubes," says their mother, Marlene, 38, "but if Ruthie and Verena wanted to do something, it was like, 'Oh, yeah, Mom, we'll just take the tank with us.' They could find happiness in things you'd never even think of looking at. That's the big message I hope people get from their lives: Appreciate what you have."

For the Cady family, the past few years held much to appreciate. Their eldest daughter, Maria, 9, was enjoying her sisters and adjusting to the attention they invariably commanded. ("Sometimes she'd say, 'How come I'm not special like Ruthie and Verena?' " says Peter, a chef and culinary instructor at a local college. "We'd always tell her she was.") The twins were usually in good health, and they were wild about the elementary school near their Cranston home. "They loved first grade," says Marlene. "Oh, and Ruthie fell in love this year, with a boy who sat near her. She couldn't concentrate on anything she was doing. It was important to Verena to protect Ruthie so that no one would tease her about it. She'd keep going, 'Come on, Ruthie, pay attention.' That was typical of them." The twins had long ago solved the who's-in-charge problem: Each of them got to make the important decisions—like whether to play cards or Monopoly Junior—on alternate days.

Always different, the twins' personalities had been growing even more distinct. Ruthie had artistic talent and longed to be a model or an actress. "She was always pointing her toes and flicking her hair back," says Marlene. Verena was the talker, the practical one. "If there was something to be concerned about," Marlene says, "Verena would be concerned about it."

It was Verena who sensed that the good times wouldn't last forever. Last January, Ruthie developed severe pneumonia, and both girls were confined to a hospital oxygen tent. Though they returned to school, Ruthie's lungs remained weak, and she needed oxygen. "We had oxygen tubes 150 feet long, running down the street, wherever they were playing. We wanted them to have as much fun as possible," says Marlene. "We were kind of sensing that things were slowing down—the doctors said they thought the girls had maybe a year left."

The twins had never been told that they might not live to adulthood, "but people would discuss their condition in front of them, so I'm sure they picked things up," says Marlene. Still, she was astounded when, on the twins' seventh birthday in April, Verena calmly remarked, "Wouldn't it be surprising if we lived till we were 9? But I don't think it's going to happen. I think that pretty soon we're going to die. But don't worry, Mom. God told me he'll make sure everything's all right." Says Marlene: "It took all my self-control not to burst out crying."

By May, Verena needed extra oxygen too. One morning, after a night disturbed by episodes of painfully rapid heartbeats, a condition the twins had long been taking medication for, Verena began making plans for their deaths. While Ruthie listened ("It was as if she knew Verena would handle everything," Marlene says), Verena "gave me a list of friends she wanted at the funeral, friends I should send flowers to, and said she'd need to have her and Ruthie's names put someplace so they'd be remembered," says Marlene. "She was totally calm." Her self-possession seemed almost otherworldly. Says Peter: "I don't know where she got it. I have 29 years on her, and I'll never have that kind of wisdom." By mid-July, the girls were back at Children's Hospital in Boston. Tests determined that Ruthie's lungs were in the final stages of deterioration. The family knew the end was near.

Very early on the morning of the 19th, says Marlene, "I went in to lie down with them. I could see that there was no way they could get comfortable. I just changed their positions for them, every two minutes or so." Shortly after 8 they called for Maria, who came in from playing to dispense hugs and kisses. Not long afterward "Verena said, 'We're dying now, Mommy,' " Marlene says. "Then she looked at Ruthie and said, 'Is Ruthie already dead, Mommy?' I said, I think maybe she is. Doesn't she look peaceful now?' Verena said yes, she thought so. Then she said, 'You'd better get Daddy now.

Summoned from outside, Peter arrived to witness deaths that were as extraordinary as the lives the children had led. To her parents' surprise, Ruthie, who moments before had seemed lifeless, looked up at her father and spoke. "I'm not comfortable here, Daddy," she said. Then her eyes rolled back.

Minutes later, after Peter and Marlene had told her how much they loved her, Verena joined her twin.

"Ruthie and Verena taught us so much," says Marlene. "They were a perfect example of sisterhood and unity. It would make a pretty neat world if we all lived the way they did."