How is it that we enter the 51st season of 60 Minutes and are only now profiling the most successful musician and composer in popular music history? Maybe it's because it's nearly impossible to try and find something new or surprising to talk to Sir Paul McCartney about. How do you jostle a new memory from a Beatle who, over the decades, may be the most written about person on the planet?

Well, as the Beatles' "White Album" is about to turn 50 years old, we decided to go for it.

Mr. McCartney was funny and reflective as we used rare photos and film to walk him through some very personal Beatles stories, and wondered who, at the age of 76, he is still trying to impress. But let's start with a bit of a revelation, the man who has sold an estimated billion records and may be rock and roll's best bass player can't write or read music.

Paul McCartney: It's-- it's embarrassing.

Sharyn Alfonsi: Is that true?

Paul McCartney: I don't read music or write music. None of us did in the Beatles. We did some good stuff though. But none of it was written down by us. It's basically notation. That's the bit I can't do. 'Cause I don't see music like that. I don't--

Sharyn Alfonsi: That's interesting. You don't see music like that?

Paul McCartney: Yeah, I don't see music as dots on a page. It's something in my head that goes on.

From his first countdown, on their first song, off their first album, that "something" has translated globally and across generations.

Today, McCartney is still seeing music in his head.

Sharyn Alfonsi: How do you feel about this one?

Paul McCartney: I'm proud of it… I like this one.

"This one" is McCartney's latest album. "Egypt Station" just debuted at number one.

Sharyn Alfonsi: When you are writing these songs, who are you trying to impress?

Paul McCartney: (LAUGH) Everyone. I suppose--

Sharyn Alfonsi: That's a tall order.

Paul McCartney: Yeah. Well, that is an impossible order, you're right. It doesn't stop me tryin'.

Sharyn Alfonsi: But don't people always say, "I love it, Paul. You're wonderful."

Paul McCartney: That-- that is an occupational hazard.

We spent two days with 'Macca,' as friends have called him. Since Liverpool, touring his relic filled recording studio on the South English Coast.

Paul McCartney: This was at Abbey Road.

Sharyn Alfonsi: Uh-huh.

Paul McCartney: And this is-- like, the fireman rushes in… (McCARTNEY PLAYS CHIMES)

And we were surprised to find Paul McCartney, at 76, seems to feel the same need to prove himself as he did when he was a teenager.

Paul McCartney: I think people worry about things. And it doesn't matter how elevated you get, or your reputation gets, you still worry about things. I mean, I'm sure--

Sharyn Alfonsi: What are you worried about? What else do you have to prove?

Paul McCartney: I've heard people say that about me. Oh, you know, he wants to be liked. But I'm going, doesn't everyone?

Sharyn Alfonsi: Do you worry more now than you used to.

Paul McCartney: No, it's just who I am maybe, you know for instance, when we'd done, we were now famous with the Beatles and we had done "Revolver," one of the early Beatle records. And-- I got the horrors one day. I thought it was outta tune. I thought the whole album was outta tune. I listened to it and for some reason just, like, oh my god. And I went to the guys, I said, "It's outta tune. It's outta-- I don't know what we're gonna do." You know? And they said-- and they got a bit worried and listened to it. They said, "No, it isn't." I go, "Oh, okay.

After the Beatles broke up, I kinda got accused of being the one that broke 'em up and that we always had terrible relationships. So this always reminds me of how happy we were together.

We were with McCartney as he prepared to tour, warming up with some surprise shows, including this one, at Liverpool's Cavern Club.

The Beatles played this club almost 300 times. And while McCartney's fans know every word to "Hey Jude," "Yesterday" and "Band on the Run," we were surprised who didn't.

Paul McCartney: When I'm doing shows I listen to a lotta music, Beatles music, Wings music, to see what ones we're gonna do. And to learn them.

Sharyn Alfonsi: Yeah. What do you mean, you've forgotten them?

Paul McCartney: Yeah.

Sharyn Alfonsi: Really?

Paul McCartney: There's too many. Too many words. (LAUGH) Too many notes. They're very hard. I mean, you know, it's not like they're all three chords.

McCartney is at least a co-author of rock-and-roll's constitution. Credited with a stunning 29 number-one hits, McCartney's work has been covered by icons from almost every musical genre.

Famously, John Lennon and Paul McCartney became songwriting partners as teenagers. One a full-throated, lyrical rock and roller, the other a musical polymath with a gift for melody and experimentation.

Those first flute-toned notes on "Strawberry Fields," John Lennon's masterpiece, were McCartney's idea.

Sharyn Alfonsi: Were you guys competitive, writing with each other? Or did you complement each other?

Paul McCartney: Me and John? Yeah, we were competitive, yeah. Not openly, but we-- we later admitted, "Yeah, you know, so Paul's written a good one there, I better get going." And I would similarly-- "Hmm, that's a bit good, right, here we go, come on." If he'd have written "Strawberry Fields," I would write "Penny Lane." You know, and it's-- he's remembering his old area in Liverpool, so I'll remember mine.

Sharyn Alfonsi: And when that happened, did you compliment each other?

Paul McCartney: Once—

Sharyn Alfonsi: One time--

Paul McCartney: --John gave me a compliment.

Sharyn Alfonsi: In how many years? (LAUGH)

Paul McCartney: It was only once, the whole time. No, I think it was "Revolver," but it was "Here, There and Everywhere" was-- was one of my songs on it.

Paul McCartney: And-- but John says, just when it finishes, "That's a really good song, lad. I love that song." I was like, "Yes, he likes it." You know, and I-- I've remembered it to this day. It's pathetic, really.

Sharyn Alfonsi: Did you ever heap praise on him?

Paul McCartney: Yeah, I would tell him his stuff was great. You'd normally have to be a little bit drunk. It helped.

You don't need to be a Beatle fan to appreciate the importance of this part of London. For tourists it rivals Big Ben or trying to catch a glimpse of the royal grandkids. Abbey Road Studios, where Paul, John, George and Ringo, along with producer George Martin, began denting pop culture, first with jangly, flirty harmonies. And later by exploring, then defining what music could be.

But during tense sessions for what would become the "White Album," 50 years ago, the Beatles, still only in their 20s, began breaking apart.

Paul McCartney: I love this picture. Yeah, this is very special for me—this series. Because after the Beatles broke up, I kinda got accused of being the one that broke 'em up and that we always had terrible relationships. So this always reminds me of how happy we were together. I'm checking some lyrics or something. And it's just great the-- the way John's sort of just smiling. We're obviously just two mates, you know.

Taking the pictures was Paul's first wife, the late Linda McCartney. Her photos, from "Life In Photographs," are intimate and historic.

Paul McCartney: We were in the studio downstairs puttin' finishing touches to the album. And-- we had another title going on that we didn't really like. So I just said, "Hey, why don't we just call it Abbey Road? And what we could do, we just go right outside, walk across the crossing. (SLAPS) It's done." You know, and it was like, "Yeah, okay." Everyone agreed. So—

Sharyn Alfonsi: Where-- where were your shoes?

Paul McCartney: I had sandals on.

Paul McCartney: But I just left them over here to the left. 'Cause it was a very hot day.

Paul McCartney: This is outside Abbey Road after we'd made the Abbey Road crossing picture. And I remember talking to John about his taxes. Someone had said to me, "You better warn him 'cause he doesn't know what's going on."

Sharyn Alfonsi: About taxes. That's why you have this glum look on your face?

Paul McCartney: (LAUGH) That's maybe why he's got the glum look. I've got the, "I need to talk to you about your taxes look." (LAUGH)

Sharyn Alfonsi: What about this one?

Paul McCartney: This is-- in our back garden. And-- Yoko's in it. And you could see by the looks on our faces all-- all except John we're kinda going-- "Why is she in the Beatles' photo?"

Sharyn Alfonsi: But how did that--

Paul McCartney: Because--

Sharyn Alfonsi: --happen?

Paul McCartney: How did what?

Sharyn Alfonsi: That she was allowed in the photo?

Paul McCartney: 'Cause they were madly in love. And John wanted to take her everywhere. I think none of us dared say, "John, you know." But we all felt it. So it was a bit awkward for us I must admit.

Sharyn Alfonsi: This is my very favorite--

Paul McCartney: Oh, yeah.

Sharyn Alfonsi: --photograph.

Paul McCartney: That little baby in my jacket now has four children of her own.

McCartney credits his love of family and music to his father, Jim, who raised Paul after his mother died when he was just 14. Today, the man who wrote "Mother Nature's Son" has four grown children, a 14-year-old daughter and eight grandchildren.

We also showed mccartney what amounted to home video of he Beatles.

Paul McCartney: Here we are. It's cold. And we're coming out.

From their last live performance together.

Paul McCartney: There's me testing the roof.

The Apple rooftop concert in London.

Paul McCartney: Now, that's the thing, you know. Good little band.

Sharyn Alfonsi: Sounds pretty good.

Paul McCartney: It does, yeah.

Million-dollar business conflicts and creative differences were carrying a lot of weight, but watch them try and hold back smiles as they rock through a song they wrote as teenagers.

Sharyn Alfonsi: I think you see it here.

Sharyn Alfonsi: That doesn't look like a band about to break up. That look between you--

Paul McCartney: Yeah, I know, it's funny, isn't it, yeah. It was when the business crept in and it got a bit sticky, you know. It never got really that bad. But we do-- we ended up bitching at each other from afar, you know.

The business part of things worked out pretty well for Mr. McCartney, he's worth more than a billion dollars. But for the last seven years he says his good fortune is due to his wife, Nancy, an American, who he calls beautiful and real. Though, he realizes it's probably tricky being married to one of the most famous faces on earth.

Paul McCartney: Just bein' recognized by everyone. I mean, you don't always need that. It's-- it's a very difficult thing, you know, 'cause you-- you don't want to sort of be mean to them, 'cause they're nice people, they genuinely like you. But you have to draw the line. These days everyone's got a camera.

Sharyn Alfonsi: Everyone has a camera--

Paul McCartney: So-- so the first thing, when I see people, they go-- (RUSTLING) and they're not-- they can't say anything. They just go-- "We'll do a picture"-- I say-- and I say, "I'm sorry, I don't do pictures. But I'm very happy to shake your hand and we'll have a chat."

No selfies? Who cares? The headline is if you meet Paul McCartney, you can have a chat! And who doesn't want to have a chat with a Beatle?

Sharyn Alfonsi: Where are you most content? When are you most content?

Paul McCartney: I live on a farm in England, it's about 20 minutes from here. And for me, it's great because I can be in, like, Australia, playing to 40,000 people two days before. Now I'm back on the farm and I'm on my horse, and we're goin' into the woods, and it's quiet, little birds singing. So, that is very satisfying and it's a great balance.

Sharyn Alfonsi: What's the biggest misconception about you?

Paul McCartney: I don't know really. I don't-- I don't hear about them. I don't know what people think about me. I can-- I can try and guess. I'll-- I'll-- I'll tell you what, "You must have no insecurities." Just like anyone else, you have insecurities. 'Cause everyone has them. And no matter how high and great and wonderful you get, there's still something will make you worry.

Sharyn Alfonsi: Were you ever just gonna go, "I'm good, I did it all?"

Paul McCartney: I would like to think I could do that. But I think it would be boring and I think I'd sort of give up trying. And I quite like that I don't think I've done—good enough yet.

Imagine that, Paul McCartney won't just let it be.

This story was produced by Bill Owens and Kara Vaccaro.