Of all the acts on our countdown of the Top 100 Classic Rock Songs, none gave us a bigger challenge than the Beatles. Although the decision to only include one song per act allowed for a greater range of bands, it also meant that the entire catalog of the Beatles, the greatest and most diverse in all of rock, had to be boiled down to one -- and only one -- song.

Nearly every Beatles album contains at least one tune that, depending on how you feel that day, qualifies as the Greatest Rock Song Ever. That's not even including the non-LP singles that comprised the Past Masters set, which had such hits as "I Want to Hold Your Hand," "She Loves You," "Revolution" and "Hey Jude." Any one of those could top this list, and it would be completely justified.

In addition, picking one song could also suggest that we were taking sides in the 40-year Lennon vs. McCartney debate, something we prefer not to engage in. We love John and Paul equally, and even though their solo careers had plenty of high points, they were never as good apart as when they worked together, giving their input -- a bass line, a lyrical tweak, a smile of approval from a friend and fellow genius -- to each other's songs.

So, our selection of "A Day in the Life," deserving as it is at No. 5, is also a symbol of all the brilliant music the Beatles made throughout their career. Of all the Beatles' songs, it is the ultimate Lennon-McCartney composition, even more so than the early days where they actually did write together in McCartney's front room. Back then they were still learning the rules of songwriting -- but by the time they assembled Sgt. Pepper's Lonely Hearts Club Band, they were breaking them.

On "A Day in the Life," Lennon and McCartney combined their individual songs to create something greater than the sum of its parts. Throw in some acid, an orchestra (dressed in formal outfits accented with fake noses or gorilla paws), brilliant drumming by Ringo Starr and three grand pianos holding an E major chord for 40 seconds and you have one of the few rock songs genuinely worthy of the term "masterpiece."

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