Even though Frank Sinatra dubbed this the "best Lennon/McCartney love song" while covering it at his shows, this is actually one of the rare songs that George Harrison penned. As one of the most famous love songs, it was inspired not by Harrison's model wife at the time, Pattie Boyd, but by Harrison attempting to capture Ray Charles' bluesy tone.

Paul McCartney was always very close to John Lennon's first son, Julian. While Lennon was dealing with the divorce of his first wife, McCartney was inspired to write this song in an effort to cheer up Jules (changed to "Jude" for lyrical aesthetic) up. However, the elder Lennon felt the lyrics were also reaching out to him and his budding relationship with Yoko Ono.

Lennon lost his mother, Julia, while he was a teenager, and the trauma continued to haunt his creative endeavors throughout his life. This song from The Beatles (a.k.a. The White Album) is a much softer homage to his loss than his later recording, "Mother," on his solo album John Lennon/Plastic Ono Band.

While studying Transcendental Meditation with the Maharishi Mahesh Yogi in India, many famous faces joined The Beatles. Among them were Mia Farrow and her sister Prudence, who was notoriously shy, which inspired this ode to helping her break out of her shell.

This multi-layered song contains several references in the lyrics. Lennon drew inspiration from the death of Tara Browne, would-be heir to the Guinness brewery fortune, as well as Timothy Leary's "tune in, turn on, drop out" pro-LSD motto with the line "I'd love to turn you on." In the verse beginning, "I saw a film today, oh boy…", Lennon is referencing his short-lived acting career and the movie flop he starred in, How I Won the War.

The ladies in McCartney's life inspired several classic love songs, but his muse in this cheerful ditty was actually his gigantic, fluffy sheepdog named Martha.

Since its release, Lennon and die-hard Beatles fans have battled the assumption that the lyrics and title were used as code for LSD. Lennon attests the song was inspired by an innocent nursery school drawing by his son, Julian. The "Lucy" in question was Lucy Vodden, 43, who was at nursery school in Weybridge with Julian and passed away in 2009.

Despite the LSD controversy around "Lucy in the Sky With Diamonds," The Beatles didn't shy away from the subject of drugs in their songs. Many theories debate who the titular doctor in this song refers to: Lennon and Harrison's dentist laced their coffee with LSD one evening without telling them; or Bob Dylan, who earlier introduced them to marijuana; or possibly an infamous New York "doctor" known as Dr. Feelgood, who supplied his patients with anything they asked for Lennon also sometimes claimed to be the inspiration himself.

This song could have been titled "He Said He Said," since the person who actually inspired this song was actor Peter Fonda. While most of the band (sans McCartney) partied in Los Angeles, Harrison became uneasy on a bad acid trip and felt like he was going to die. Fonda consoled him by saying, "I know what it's like to be dead" and explained his childhood near-death experience. As a result, Lennon was inspired to pen this eerie tune.

The lyrics for this Harrison number come straight from a box of chocolates. Legendary guitarist and Beatles friend Eric Clapton had a bit of a sweet tooth and, after being warned by his dentist to cut back, Harrison wrote this song as a joke, claiming Clapton would "have to get them all pulled out" if he continued to indulge.

In this song, Lennon asks The Beatles' longtime manager, Brian Epstein, "how does it feel to be one of the beautiful people" following the band's ultra-success. Epstein was always known for enjoying the finer things in life and sadly died not long after the release of this single.

After Epstein's passing, there were several issues with finding a replacement manager. The bandmates disagreed over who should be chosen for the job but eventually settled on Allen Klein, who also co-managed The Rolling Stones. This did not sit well with McCartney, who vented in this song his frustration with Klein's mishandling of their money.

By this time in the band's history, Lennon was rarely seen without Yoko Ono at his side -- including at the recording studio. The other Beatles were uneasy with her presence, but Lennon couldn't care less and penned this song with the "monkey" referring to Ono. McCartney, however, believed the monkey was more of a reference to Lennon's growing heroin habit.

While it would be nice to believe this song was about a peacefulness between Lennon and McCartney, it actually referred to McCartney and wife Linda's routine of driving around the countryside together, getting lost on purpose and exploring together.

Harrison sampled lyrics from "Sorrow" by American band The McCoys, repeating "with her long blonde hair and her eyes of blues" as the song ends. Later, Harrison became much less inclined to borrow from other songs; he was sued by representatives of The Chiffons for unintentionally using a similar music structure to their 1962 hit "He's So Fine" in his first solo single, "My Sweet Lord." Harrison eventually treated the mix-up with a sense of humor, recording "This Song" as a lampoon of the situation.

Lennon started seeing Yoko Ono just before the band's trip to study meditation in India with the Maharishi. Though he was joined by his wife Cynthia on the trip, he received several letters and postcards from the artist and began feeling increasing torn by their relationship and resultantly developed insomnia. The song also includes a shout-out to Sir Walter Raleigh, the English aristocrat who was responsible for popularizing tobacco in England, a reference to the sheer volume of cigarettes Lennon consumed in his sleeplessness.

After a professor wrote to Lennon to inform him of his class analyzing Beatles lyrics, the snarky songwriter took it as a challenge to produce the most indecipherable song imaginable. References to nursery rhymes are layered along with digs at pop culture -- most notably in the line "elementary penguins singing Hare Krishna," which offended his bandmate and budding Hindu George Harrison.

A year after Lennon took a dig at Hare Krishna, he changed his tune quite literally with this celestial song that includes a chorus of "jai guru deva om," a mantra that loosely translates to "hail the divine guru."

In this song, Lennon taking a meta look at the band as a whole. The "Paul is Dead" rumors claiming McCartney was replaced by a lookalike were circulating at top speed at this point, so to egg them on, the Egg Man explained that the "Walrus" was Paul, inciting conspiracy theorists.

This song, with a deceitfully cheery tune, was inspired by Lennon's extramarital affairs. At the end of the song, he croons, "so I lit a fire, isn't it good, Norwegian wood," and he isn't talking about using the fireplace. The song is actually talking about setting fire to a woman's house after she leaves the next morning, though Lennon didn't actually do anything like that (we think).

Inspired by longtime producer George Martin showing Lennon a gun-loving magazine's headline, the singer shifted gears midway through the song to lament "I need a fix 'cause I'm goin' down…". This referenced his growing heroin addiction. Later in his solo career, Lennon would release the single "Cold Turkey" about breaking away from the drug.

The band liked to be playful with its background vocals and frequently used silly references or phrases to harmonize behind the lead lyrics. In this case, careful listeners will hear the French children's rhyme "Frère Jacques" behind McCartney's lead vocals.

Prior to "Paperback Writer," the band had a good laugh over secretly singing "tit tit tit tit tit" obscured in the background vocals of this song.