NEW YORK – For Paul McCartney, songwriting is not only a job, a craft and an emotional outlet. It is a compulsion and a craving.

“People say, ‘Well, why do you still write songs’? And it’s just because I love it. I’m addicted,” he said in an interview at Boulevard Carroll, a warren of recording and rehearsal studios on Manhattan’s Far West Side, where McCartney, 83, had just wrapped up an afternoon of band practice for the season finale of Saturday Night Live.

“Out of a black hole comes forth milk and honey. And it’s so great, the feeling.”

Prolific as he has been – through the Beatles, Wings and solo albums – McCartney does not follow any songwriting discipline or routine.

“I’ll just be somewhere, and with some time to spare, and my guitar will be there, or I’ll be near a piano. And the urge will take me,” he said.

“Whenever I’ve hit something, it’s just like, ooh, wow. It’s a great feeling. You know, the whole creative thing is a great thing. I say it beats working.”

Even for a rehearsal, McCartney was nattily dressed. He sported a blue jacket, a black shirt with pink pin dots, black pants, white-soled shoes like karate slippers and socks with a psychedelic design of blue bubbles below a bright yellow stripe.

A few days afterwards, McCartney would perform on SNL, playing old and new songs, including Days We Left Behind from his new album, The Boys of Dungeon Lane.

Then, five days later, McCartney was the surprise final guest on The Late Show with Stephen Colbert, onstage at the Ed Sullivan Theater, where the Beatles made their North American debut in 1964. As a musical finale for Colbert, he sang the Beatles’ Hello Goodbye.