Pianist since childhood; theory brain arrived with adulthood. The moment harmony clicked — that a chord isn't a thing but a tension with an address, always pointing somewhere — was one of the great lightbulbs of my life.
Thread for: theory questions at any level, practice-routine talk, "what IS that chord in this song" requests, and gushing about a modulation like it's sport. Because it is.
request: the Beatles do a thing where a song feels like it "opens a door to outside". what is the door. I need to know the door's name
That door is usually the flat-VI (or a friend of it) — a chord borrowed from the parallel minor. The song establishes a home key, then reaches for a chord that doesn't live there, and your ear registers "we're somewhere new but I can see home from here". Listen to the last line of the "Penny Lane" chorus and you'll hear the hinge turn. Doors, addressed.