If one lives in a natural enviroment, one participades in a system. If you drink water from a spring in the mountain, catch fish in the river, plants from the earth, one will become one with ones natural enviroment, participade in its live.
The human body is about 80% water, so if you drink water only from one source, you will consist in 80% of that source. The same goes for food, so by living from the land, you can become an extension of it, taking part of the whole.
This will give you a knowledge of the whole, just as you are only one part of a larger whole, so is that part of the global whole, and that part of the universe.
If you die all that which was part of you will be returned to the whole, nothing is wasted. All is shifting , dancing exchanging.