The conversation with Carly Simon was briefly interrupted by a knock at the door of her home in Martha's Vineyard. When Simon returned to the phone, she reported, "These ravishing bouquets of flowers arrived. I had them sent to myself."

It's something Simon does periodically. "It's wonderful," she said. "You should try it some time. Whenever I feel extravagant, I have flowers sent -- with notes to myself. Something like, 'Carly, man, you're the tops.'"

Simon has a new album, "Come Upstairs," for a new record company, Warner Bros., but she has canceled a scheduled tour. She will remain close to the home she shares with husband James Taylor and their two children, Sarah Maria, 6, and Benjamin Simon, 4.

Benjamin is the chief reason for postponing the tour until sometime in the fall. He recently had his left kidney removed. "He's doing fine now," she said, "but it was pretty traumatic at the time. He kept coming down with these high fevers that could not be explained. Finally it was determined that he was born with this one kidney that was malfunctioning.

"He's running around right now with a Superman cape and stronger than ever. But it's still a case of convalescing. He wants to be with me all the time."

Simon figures the tour delay will have an added benefit. "It will give me time to get into physical shape. Not that I'm exactly weak now, but with a rock 'n' roll tour coming up, I could use a little muscle. Well, not Popeye, but just a little muscle."

The rock 'n' roll tour Simon is contemplating tells something about the new Simon album and the "new Carly Simon. The album sports a harder rock edge than any of her previous LPs.

From a personal point of view, she said, "That other Carly Simon is gone. There's nothing resembling her around her any more. I don't know where she is. Maybe she's hiding in a closet somewhere and maybe she can be retrieved one of these days.

"I guess it's true that we shed our skins every seven years. It's difficult to explain. When you're still living within the the same body, it's hard to be objective about oneself. But circumstances in my life are such and there have been changes causeing me to get outside of my old self-image. I guess I saw myself in the past as being extremely polite.

"As we get older there's a tendency to grow into a mold, become confined to a certain space. It's been said that by the time we reach 30 the personality we have is the one we're stuck with for the rest of our lives. Well, I just hate that I don't think it has to be that way if we exert pressure on ourselves, to force ourselves into being more expansive."

The one characteristic Simon is not likely to shed all that easily is her fear performing, despite the fact that there is scant evidence of that fear when she is on stage. "That's a paradox, my dear," she said. "Purely paradoxical. That's all I can say. It's not just a case of being terrified before doing a concert. The whole time I'm on stage I'm terrified. I keep thinking, 'Well, I'll finish this song and run off stage and never do it again.'"

Simon -- the daughter of Richard and Andrea Simon (of the Simon & Schuster publishing house) -- was born and reared in New York City. During the mid-1960s, while attending Sarah Lawrence College she and her sister Lucy formed a folk duet called the Simon Sisters.

"We played all of the folk clubs in the New York area," Simon said. "We used to come to Philadelphia to sing at the old Second Fret, which was a grand place. I remember we'd catch the 1 a.m. train back to New York and I'd do my school papers on the train. I finally realized you couldn't be a good college girl and live that kind of life. So I left my sister and went to live in the south of France for a year and a half with my boyfriend. I had to, well think things over."

When Simon returned to the United States she collaborated with Jacob Brackman on a collection of songs that appeared on her debut album for Elektra Records in early 1971.

Among the songs was one titled, "That's the Way I've Always Heard It Should Be," which became a hit single. The hits have been coming for Simon ever since.

Simon pointed out that her songwriting is not nearly as introspective as the public assumes. "I suppose you could call the songs introspective only in that I have sometimes used some of my feelings as a point of departure," she said, "but my feelings are fairly universal. They can't really be pigeonholed. It's like someone who writes fiction, which is all songs are.

"There was one song in particular, 'You Belong to Me,' which so many people thought was exceptionally personal. I remeber shopping in a store one day and this man came up to me, saying, 'Mrs. Taylor, Mrs. Taylor, did Mr. Taylor really do that to you?' 'Do what?' I said. The point is that the song really had little bearing on anything in my life."

The one Carly Simon song that undoubtedly prompted more of a national guessing game concerning its subject than any other was "You're So Vain." Simon remains amused over the wide conjecture, which included everyone from Mick Jagger to Warren Beatty, but if it was indeed based on any one person, she maintains the mystique.

"It's just too boring," she said.

Carly Simon and James Taylor were married in November 1972, becoming the first family of rock 'n' roll. But while this situation has placed two of the most popular songwriters in pop circles under the same roof, they have collaborated on only a few occasions.

"It's just much easier for me to work with other writers," Simon said. "James can be very assertive and he likes to call the shots. Well, my ego can't deal with that. Besides, I have a great deal of respect for James. I guess I'm in awe of him in certain ways."

On Simon's "Come Upstairs" -- her first album since leaving Elektra -- she collaborated with Mike Mainieri, who produced it.

"For me it was a special kind of collaboration," she said. "It was an opportunity for me to write the words and music, with Mike contributing certain chord changes and occasionally an important hook. Our personalities blended very nicely."

Simon said that the emphasis on a harder approach to her music on the new album was a con scious move. "Mike and I decided to really cut out on it," she said. She likened one of her songs, "In Pain," to Led Zeppelin, adding, "It's fun." And while the old Carly Simon, the polite one, might not understand any of this, she's locked in a closet someplace and the new Carly Simon couldn't care less.