I haven't seen older episodes of The Simpsons in literally years. I definitely prefer the old Simpsons like this over the modern day newer Simpsons. I feel exactly the same way about Family Guy as well.
Homer's very troubled Son Bart. Bart and Lisa's sibling rivalry brought on by being baby sat by Lisa. Seriously, Bart should of been sent too milhouse while Homer and Marge went out!
Bart hates that Lisa was left in charge of him, because he is older than her. He thinks that he should be the one left in charge of her, because she is younger and he is older.
Bart's injuries were the result of him falling down the stairs. Which he caused, by losing control, when he was jumping on his parents bed. (instead of doing what Lisa told him to do.) That's "cause and effect." His injuries were his own fault.
