identify this movie - A film about a boy and his big idea for society?

This is what I remember:

A boy, living on a farm or so, tells someone, could've been the postman, about his idea, his big idea for society and the world. It's about being good, sharing or something similar altruistic. And the postman answers what a great idea it is and silently takes it with him. In fact he starts, by accident to spread "the idea" and then the idea gains momentum, like a big wave washing around the globe.

Then, one day, the boy has already given up on it, has forgotten about the idea or so. But in the end of the film, the idea comes back to him, when someone presents exactly his idea to him, doing good, sharing or similar. The boy's idea has come full circle.

Can anyone identify this plot. Can anyone name this movie?