I've been discussing an article about visual illusions in class this week. (It's not the same as an optical illusion.) You can see an example of the visual illusion here. It looks like the tower on the right is leaning more than the tower on the left. But really, it's two identical photos side by side.
© 2007 Kingdom, Yoonessi & Gheorghiu (Read more about these illusions here)
When we finish reading the article and comprehend it, I ask, "So if your senses can deceive you, what exactly is reality? If we all share the same perception, does that make it real?"
We've all heard things that didn't really make a sound. I mean sometimes I think spouse has called my name and I answer, "What?" And then he tells me that he didn't say anything.
Then we talk about the expression, "seeing is believing", and the oft repeated business axiom, "Perception is reality." It's made for some interesting conversation.
I had a (fervently religious) student who exclaimed, "This is philosophy! I'm here to learn English."
That certainly popped my soufflé. So I sighed, and moved on.