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"The Last Supper" is a painting of a moment Jesus had with his 12 followers, when he announces one of them will betray him. That the betrayer will take the same bread Jesus will take that bread. Many of the disciples look shocked, surprised, angry, or just seeking an explanation. The disciples are shown at the same side of the table so that we can see everyone's facial expressions to the news that Jesus has announced. Leonardo wanted us to see the facial expressions and gestures of everyone in the painting. I think Leonardo's art technique that he used was symbolism. He symbolizes certain items and gestures as a way of identifying a person's character. For example he portrays Judas knocking over a cellar of salt. That action is a near Eastern notion of "betraying the salt" which means betray one's master. Judas does betray Jesus and the painting kind of predicts that.
One interesting invention that Leonardo Da Vinci created was the ornithopter. It is a device like the hang glider. People can fly off a cliff with it, much like a bird flies with its wings.
Please let me know if you need any clarification. I'm always happy to answer your questions.
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