A man is whispering sweet nothings to a Grecian urn, an ancient Greek pot that is covered in illustrations. He thinks the pot is married to a guy named "Quietness," but they haven’t had sex yet, so the marriage isn’t official. He also thinks that the urn is the adopted child of "Silence" and "Slow Time."
Then the speaker gives us the urn’s profession: it’s a "historian," and it does a much better job of telling stories than the speaker possibly could. The speaker looks closer at the urn and tries to figure out what’s going on in the pictures that are painted on it. Illustrated on the urn is some kind of story that might involve gods, men, or both. It looks like a bunch of guys are chasing beautiful women through the forest. People are playing pipes and beating on drums. Everyone looks happy. The scene is chaotic and the speaker doesn’t know quite what’s happening.
Not only is the urn a better storyteller than the poet, but the musicians in the illustration have sweeter melodies than the poet. The poet then tries to listen to the music played by the people in the image. That’s right: even though he can’t hear the music with his ears, he’s trying to listen to it with his "spirit." He looks at the illustration of a young guy who is playing a song under a tree. Because pictures don’t change, the man will be playing his song as long as the urn survives, and the tree will always be full and green.
Then the speaker addresses one of the guys who is chasing a maiden, and he offers some advice: "You’re never going to make out with that girl, because you’re in a picture, and pictures don’t change, but don’t worry – at least you’ll always be in love with her, because you’re in a picture, and pictures don’t change."
The speaker thinks about how happy the trees must be to keep all their leaves forever. It’s always springtime in the world of the urn, and every song sounds fresh and new. Then he starts talking about love and repeats the word "happy" a bunch of times. He is jealous of the lovers on the urn, because they will always be lusting after each other. Seriously. He thinks the best part of being in love is trying to get your lover to hook up with you, and not the part that follows. We’re starting to think that the speaker needs a cold shower. The word "panting" threatens to send the poem careening into X-rated territory.
Things were getting a bit steamy, but now the speaker has moved to a different section of the urn. He’s looking at an illustration of an animal sacrifice. This is pretty much the cold shower he needed. A priest is leading a cow to be sacrificed. People have come from a nearby town to watch. The speaker imagines that it’s a holy day, so the town has been emptied out for the sacrifice. The town will always be empty, because it’s a picture, and pictures don’t change.
The speaker starts freaking out a bit. He’s basically yelling at the urn now. Whereas before he was really excited about the idea of living in the eternal world of the illustrations, now he’s not so sure. Something about it seems "cold" to him. He thinks about how, when everyone he knows is dead, the urn will still be around, telling its story to future generations. The urn is a teacher and friend to mankind. It repeats the same lesson to every generation: that truth and beauty are the same thing, and this knowledge is all we need to make it through life.