An insightful joke

The wise teacher is gazing absentmindedly out of the window. Finally she asks: “Why did some people believe that the Earth is flat?” After a short pause one of her pubils responds: “Well, it does look like the Earth is flat.” “Oh”, she responds in slight amazement, “Imagine we were living on a spherical Earth. I wonder that would look like”

I don’t remember where I read this joke and I don’t think that on the very rare occastions I have told it anybody ever found it even funny. And yet I consider it the most supreme joke I have ever come across. Not only do I personally find it funny, but it also offers the hint of an answer to the most profound question: “What is the foundation of knowledge?” or in the form I set out to address it in this blog: “Why can we know the future?”