I wrote a review about the episode "Lisa the vegetarian" (The Simpsons) on my blog.
http://cubepark.wordpress.com/2009/06/26/lisa-the-vegetarian/

After a visit at a petting zoo and the encounter with a lamb, Lisa can’t still eat meat so she decides to becomea vegetarian. Her relatives jeer her about this choice (the jingle “You don’t win friend with salad” is so weepy…). The strife with the school is really strong, too.
The barbecue organized by Homer will touch off Lisa and she’ll get so angry to the extent that she’ll throw away the main course. Lisa will take comfort in the Jet Market, where she’ll meet three other vegetarians: Apu, Paul and Linda McCartney.
This episode is a classic and it’s one of the best of the series. It faces an issue that is quite important, in a really professional way. At the same time, funny jokes never lack.
In 1995 – the year  when this episode gone in the air for the first time – there was already millions of vegetarian all over the world, but this issue hardly appeared on TV. It’s unusual to hear someone talk about the difficulty that the vegetarian face daily. The response of the people (her family, the school, etc.) toward Lisa and her choice, represent really well this facet. Lisa start figuring out this problem and she’ll find the biggest trouble in school. When she’ll voice her ideas at enmity with the teacher and the chef, it will be launched a “free-thinking alarm”. In order to confute Lisa’s ideas it will be shown a didactic film where Troy McClure explains why it’s right to eat meat. The response of Lisa’s classmate after the film (“You should be stupid to ask all that  question about meat”), prove how much feelings and children’s mind is easy to handle with small advertisements and propaganda. Just when Lisa is almost giving up her vegetarian diet, Apu will come to help her with a vegetarian hot-dog. Lisa still be vegetarian for all the Simpsons Seasons. It’s a  permanent change for this character because the people who do this kind of choice hardly going behind. It’s not like stop smoking. Often in  The Simpsons, at the end of the episode, there’s a return to begin. Not in this case. There’s a full support to the battle engaged by Lisa and there aren’t other interpretative position (it’s quite unusual in The Simpsons). On the contrary, there is an introduction on the motivations that induce a lot of people to become vegetarian, without using a petty  way.
Lisa refuses to eat the lamb cutlets ‘cause she was thinking that them came from the little lamb she was playing with. A similar scene, but a more bit strong, was described by a big thinker: “The things that we euphemistically call “meat” are, in truth, pieces of a killed animal’s corpse. Why do we have to turn our stomach in a cemetery? ” Tiziano Terzani    

Fabrizio Cirnigliaro

Thanks to Luca Feliciotto for the translation from Italian to English