Our cultural identities are determined by music, food, dance, politics, clothes, family, and friends.
Screen writer Richard Curtis has wrapped that notion around one of the most influential bands that influenced the 1960s' cultural revolution: The Beatles.
Curtis takes an enormous, fanciful leap by inviting us to believe that a solar event obliterates all electronics on our planet, causing life to take a side step into an alternative reality where no one has ever heard of The Beatles.
That is, except for struggling musician Jack Malik, who is knocked unconscious by an encounter with a bus during the solar flare.
Subsequently, he commandeers songs such as Yesterday, A Hard Day's Night and She Loves You as a vehicle to stardom.
Part of the fun is watching Jack using Post-It notes to reconstruct the songs from memory.
Only the most ardent Beatles fan could remember all the lyrics and musical techniques used to record the Beatles catalogue.
(Even Jack's vinyl albums by The Beatles have ceased to exist.)
His ability to work out the songs and put his own spin on them lands him in the land of milk, honey, money and fame.
He becomes a worldwide superstar.
Yesterday is not all about the songs: romance is at the core of the movie.
Jack's friend and manager, Ellie, bears undying love for Jack. He is oblivious to her emotions.
All she needs is love, but he is blinded by the glamour and wealth of music stardom. It really is a long and winding road to Ellie's heart.
Jack has drunk from the chalice of wealth and fame and has been rebranded as a product.
The film centres on unattainable love and the meaning of living a fulfilling life.
You're going to sing along to a catalogue of Beatles' songs that formed the soundtrack of our lives for anyone who grew up in the '60s, or are children who have dived into their parents' vinyl record collection.
The film provides a pop psychology guide to living happily, though it skirts around the realities of life and the disappointments that we encounter.
For the time you sit in the cinema watching Jack and Ellie, you feel that life can be positive, and - to take advice from another popular culture writer of his own time, William Shakespeare - by being true to yourself you can live a life of contentment.
Like McCartney and Lennon's formidable songwriting ability, director Danny Boyle and writer Richard Curtis are a winning combination.
Yesterday is an imaginative, entertaining, magical, mystery tour.
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