Delightful, Martin. I think you have found a good image to convey your message, especially because it contains its own reverse, since everyone knows that everything that goes up must eventually come down, too.
"Everything that goes up must eventually come down."
That's true, unless the leaf moves upward at 25,020 mph, which is the escape velocity from Earth's surface. Then it will never come back. I've never seen a leaf do that, however.