For those who don't know the story behind this:
Before Maggie was born, Homer Simpson worked at the Nuclear Plant because he needed the money to pay for all the debt. Once Homer Simpson finally payed the debt he quit his job to work at his dream job at the bowling alley. When Homer Simpson found out that Marge was pregnant with Maggie, he became depressed that he had to quit his job at the bowling alley because the salary couldn't support them. When Homer Simpson begged Mr. Burns for his old life back, he put a plaque that reads "Don't Forget: You're Here Forever." When Maggie was born, Homer instantly fell in love with her. When Lisa asked Homer where did all Maggie's baby pictures went, Homer explains that he keeps it where he needs it the most

A crayon gets removed from Homer's brain and he becomes temporarily smart and can communicate with Lisa, he later gets it put back in, before that, he leaves Lisa a note.
Homer's note to Lisa: I'm taking the coward's way out. But before I do, I just wanted to say being smart made me appreciate just how amazing you really are.

Barbara Bush once called The Simpsons "the dumbest thing I've ever seen" during an interview. She got a letter from "deeply hurt" Marge

Homer puts Maggie to bed and tells her he hopes she never says a word because once kids start talking they only argue. After he leaves she says 'daddy'

Bart writes a song for Lisa for her birthday to make up for always forgetting about it


Lisa, it's your birthday.
God bless you this day.
You gave me the gift of a little sister,
And I'm proud of you today.
Lisa, it's your birthday.
Happy birthday, Lisa.
Lisa, it's your birthday.
Happy birthday, Lisa.

You know, I always felt you were the best thing my name ever got attached to... I just want you to know I've always been proud of you. You're my greatest accomplishment and you did it all yourself. You helped me understand my own wife better and taught me to be a better person.

Lisa writes an essay on founder Jebediah Springfield for the town's bicentennial. While doing research, she learns he was a murderous pirate who viewed the town's citizens with contempt. When no one in the town believes Lisa, Homer says he does, he tells Lisa 'You’re always right about this type of thing, and for once, I want in on the ground floor'

Bart hatches a pair of lizards. Skinner says the lizards must be killed by law. Marge tries to convince Bart to turn them over and Bart says, 'Everyone thinks they're monsters, but I raised them, and I love them! I know that's hard to understand' and begins to cry. That's how Marge feels about Bart on the inside, so she lets him escape with the lizards

Homer sitting on his car hood watching the stars after Mona leaves and they just play that heartbreaking song over the credits. This scene has been described as one of the most emotional in the show's entirety

Homer and Marge separate because she has amnesia. Marge goes to a speed dating event, and she meets a man who shares her interests. When Marge tells him that she has amnesia and three kids, he immediately leaves. Homer scolds the man for leaving her, saying that she is the most beautiful woman he will ever meet. Marge tells Homer that even though she may not remember him, he knows the most wonderful things about her.

Homer uses the Springfield Nuclear Power Plant's medical insurance plan to buy Dimoxinil, a miracle hair growth formula. After applying the drug, Homer wakes up the next day with a full head of hair. He loses the hair again later in the episode. Homer tells Marge he is afraid she will love him less now that he is bald again. Marge holds him in her arms and they sing "You Are So Beautiful" together.

Homer couldn't build a functional robot and didn't want to disappoint Bart so he disguised himself as one and took beatings in Robot Wars. 

Abe sent away Bongo, Homer's childhood dog, away to a farm in attempt to save him from Mr. Burns. Homer didn't understand and was furious at Abe, especially well into adulthood. Homer thought that Bongo would forget about him until Abe showed him a photo from years later of. Homer was happy to see that Bongo was sleeping on his old sweatshirt and that he hadn't forgotten Homer.

The scene where Bart is older and laying in bed, with photos of cherished memories around him