In her first grade classroom, a young teacher was starting to explain the theory of evolution to her students.

She directed her first questions to Tommy in the front row.

Teacher : Tommy, do you see the tree outside?

Tommy : Yes.

Teacher : Tommy, do you see the grass outside?

Tommy : Yes.

Teacher : Go outside and look up and see if you can see the sky.

Tommy : Okay. (He returned a minute later) Yes, I saw the sky.

Teacher : Did you see God?

Tommy : No.

Teacher : That's my point.

We can't see God because...