The Simpsons: 10 Utterly Heart-Breaking Moments You'll Never Forget

7. Lisa's First Word

The many flash-back and flash-forward episodes we've seen in The Simpsons might feel like fillers to some, but they are often the source of the best revelations, answering questions that underpin the entire show, like why Marge is with Homer, and why anyone would hire Homer.

"Lisa's First Word" explores the relationship between Bart and Lisa in the best possible way, proving that the two have underlying love for one another that adds a completely different edge to their subling rivalry dynamic.

As their attempts to get Maggie to speak fail, Homer and Marge tell the story of how Bart hates Lisa when she was born, and tried to give her away, before failing and vowing to run away himself, right up until Lisa says her first word - "Bart." It's a very sweet episode, and crucially it adds something we hadn't seen between Bart and Lisa, which added a touching note to their relationship.