Mother's Day 2014: The Beatles are known for revolutionizing the world of popular music, turning love songs on their head and ushering in an era of love and peace. But even Beatles had mums. John Lennon and Paul McCartney both lost their mothers at a young age, Paul was fourteen when his mother died of breast cancer and John was 17 when his mother was struck by a car driven by an off-duty policeman. According to Hunter Davies in the first official Beatles biography, Harrison kept a close eye on his own mother after joining the two older musicians.

The Beatles recorded classic tributes to their mothers. But they weren't obvious. The songs spoke to the pain of losing them and the hope they inspired in the British musicians.

YESTERDAY

Yesterday, by Paul McCartney is the most-covered song in the history of popular music. It has been on and off the charts since the Beatles' original 1965 version, which first appeared on their Help soundtrack, not as a single. An entire book was written on the song, best known as the song Paul heard in a dream and originally titled "Scrambled Eggs." Paul later changed the lyrics and has since revealed that the song was composed about mother, who died when Paul was fourteen.

LET IT BE

Let It Be, sometimes regarded as a spiritual song, is also about the midwife who gave birth to the future Wing. The mother Mary, who speaks words of wisdom, is Paul's mother, Mary. Paul who never hid his own professed atheism, even in the earliest Beatle interviews, was not singing out the Virgin Mary. Paul had a history of hiding meanings in songs, though. Paul calls "Got to Get you into My Life," a Motown-influenced piece off Revolver, his "love song to pot." And who really knows what he was carrying through airport security in "I'm Carrying."

JULIA

"Julia," from The Beatles (White Album), is named for John Lennon's mother, who was run over and killed by a drunken, off-duty cop when John was seventeen. A soft and beautiful ballad, it is the only song in the Beatle catalog to feature just John and an acoustic guitar. John never got over his mother's death and continued to deal with it through song in his solo career with haunting songs like "Mother" and "My Mummy's Dead." Yoko Ono means ocean child in Japanese and Lennon called Yoko mother after the birth of their son Sean.

ALL THINGS MUST PASS

George Harrison's "All Things Must Pass" was also written his mother and not about the impending break-up of the group as has been reported. Although he recorded versions with the Beatles during the White Album sessions, he never released it until after the Beatles broke up.

MOTHER

Ringo Starr revealed in the Anthology Series that he used to sing "Motherless Child" for his mum.