"All My Sons" is my favorite:
"We used to shoot a man who acted like a dog, but honour was real there ...But here? This is the land of the great big dogs, you don't love a man here, you eat him. That's the principle; the only one we live by - it just happened to kill a few people this time, that's all. The world's that way..."
This is the kind of stuff that should be in every English curriculum in every high school in the United States because it teaches us about duty, honor, compassion, responsibility and ethics, values that seem to be sorely missing from todays world.
"Once and for all you must know that there's a universe of people outside, and you're responsible to it."
It rings as true today as it did in 1947.