It's funny, but even though this is one of the shortest animes I have ever watched, it still is one of those with the deepest meaning in it.
It is just like a insight in the human mind. The more you give, the more you share with others, the better you feel, the merrier the company and the bigger your home, life and heart. But who wants to have everything for himself and himself alone will be left with nothing in the end and fall down from his imaginary house.
I can just recommend everyone to watch it, it is very cute in the way of art and the short, deep story is simply amazing :)