The only source of knowledge is experience.

The balance between economy and ecology is the core of modern forestry.

世界是我们共享的梦。

If you want to live a happy life, tie it to a goal, not to people or things.

只有当人认识到自己对别人的依赖时，他才是真正自由的。

我们今天种下的每一粒种子都是对后代的承诺。