old buddhist man is raising a child and teaching him the ways of life. The movie follows the pattern the title suggest. Starts off in spring with the kid like 10 years old, learns a lesson, then it's summer and he's like 20, more things taught, fall he's 30 or so, winter he's like 40 and when spring rolls around, he then becomes the old man and is teaching a child himself.
I don't want to really say more than that incase you end up watching it, but it's basically a buddhist way of life and some varied teachings of it and the journey of a boy to man kind of deal.