It's a lot like Mozart and Haydn--two of dozens of very competent composers all writing in the same late-eighteenth-century classical style in which there were clear-cut ways to compose a piece. What set Mozart and Haydn apart from their contemporaries, and what makes their work still popular today, was the inventiveness with which they realized those basic conventions. The same holds true for the Beatles.
The Beatles followed basic pop forms, but they inevitably came up with a peculiar ending or an odd bridge that catches the imagination. One of their classic early hits is "She Loves You." Everyone knows the refrain--"Yeah, yeah, yeah." It's the hook of the song, it stays with the listener. But at the end of the song--"yeah, yeah, yeah, yeah"--the last note sticks out. It's a little off. That chord was a dime a dozen in Broadway show tunes. But it wasn't something that had been heard before in rock-and-roll. It was something that, right away, set the Beatles apart.
When studying classical music, it's usually very clear who composed which compositions. That's certainly true with Beethoven. When you're talking about the Beatles as composers, however, it's more complex. The Beatles were a performing group. Sometimes they collaborated. Sometimes they didn't. So it wasn't always clear who wrote which songs or which parts of which songs.
John Lennon, Paul McCartney, and George Harrison were the principal songwriters. George was crowded out by the older, more dominant Beatles, John and Paul, so in the end, there are only about 20 of George's songs commercially recorded. The rest of the Beatles' numbers--around 180--are credited to John and Paul jointly. The two did collaborate early in their career, sometimes truly working together as equals, sometimes one helping the other out with little suggestions. But, as their careers unfolded, each went his own way. Even though they were always jointly credited, many songs were not collaborations at all. So how do we know who wrote what? We can begin with interviews. It's nice when both John and Paul agree. But sometimes John said,"I wrote most of that," and then Paul said later, "No, I wrote that." Then we have to rely on stylistic evidence, on what we know each tended to do musically. But what happens if Paul was imitating John's style?
To complicate things further, their producer, George Martin, often called "the fifth Beatle," was involved in the process. He was a very well-trained musician, and the Beatles didn't read music--so Martin helped out. For example, Paul couldn't write the notes for a trumpet part he added to "Penny Lane," so he came to the studio and sang them. Martin composed a score for that part. Who, then, wrote it? That's why it's difficult to talk about the Beatles as composers. But we can talk about the Beatles' records, their songs, and the conventions they used.
The beatles first began to record commercially in 1962 and broke up in 1970. The eight years of their recording career can be divided into three periods: the early, the middle, and the late. The early songs, those that grew out of late '50s styles, were written to be performed live. The band, then with the so-called mop tops and Edwardian suits, was limited to what it could do on stage--guitars, bass, drums, and occasionally a piano.
After they released Rubber Soul in 1965, they grew tired of touring and giving live concerts. This sparked their middle period when they spread their wings as musicians and started to incorporate lots of other instruments into their songs. In "Yesterday," they used a string quartet. Paul, probably the most talented musician in the group, added the unusually high trumpet part to "Penny Lane." George added the sitar and various Indian drums.
The band was pushing the envelope of technology and changing the parameters of rock-and-roll. Suddenly, "rock" didn't describe their music. "Pop" didn't describe it. They were no longer a conventional rock group. You could no longer go to a concert and hear the Beatles. They couldn't reproduce all of the sounds live. It would have been like trying to play an orchestral score at home on the piano. Their middle songs only had life as records. That was unusual in rock-and-roll as was the idea of the "concept album," which they brought to light with the release of Sgt. Pepper's Lonely Hearts Club Band in 1967. But these conventions were very distinctive of the Beatles. Around this time the Beatles began to promote their songs using promotional films--forerunners of today's music videos. Again, they were way ahead of the curve.
Their late period really took off in 1968 when they released what has come to be known as the White Album, a 30-song set, which includes "Dear Prudence," "Piggies," and "Helter Skelter." By this time, though, they were starting to break apart. Each had developed his own style. Paul tried to persuade the band to head back to its roots, to collaborate again, and they came together for one last album, Abbey Road, which was recorded after but released before Let It Be. But they had gone too far, learned too much, and become too sophisticated to ever really go back. In many ways, the Beatles broke down the doors for rock music. Before them, musicians rarely wrote, recorded, and performed their own songs.
Elvis Presley was a great performer, but he didn't write his own songs. Cole Porter and George Gershwin were fine composers but not necessarily dominant performers. The Beatles did it all. After the Beatles, songs didn't have to be just two-and-a-half minutes long. Bands could incorporate other musicians, they could add other noise, speed up their songs, alter their voices. They could make concept albums and even videos. The Beatles weren't necessarily the first to do these things, but they were the ones groups looked to for guidance.
And, simply, they wrote great music. Their songs are well crafted. They have good tunes. They're effective. They're powerful. They're moving. Clearly, the Beatles are the most accomplished rock musicians we've had.