This exercise is a thought experiment.
In order to understand more about one's own life, it can be helpful to explore how we define terms like "life" "living" "natural" "nature" and "man made." By understanding more about what we consider and feel to be "live" we might come in touch more with the life within ourselves.
Please do take the time to ponder the questions asked. If you only read through this thought experiment it will have little value for you.

Assume for the time being, that you come from Mars, or some other distant place, and that you know nothing at all about life on earth.
You are given a long winded explanation about how to discern what is man made and what is natural. You say that you feel like you have some reasonable idea as to which is meant to be which.

You are then shown a conch shell and some children's "Silly Putty" and asked which one has been created by the intelligence of man and which one has been created by the intelligence of evolution.
Which one will you say is which? Why?

Next you are shown some "Silly Putty" and some mud. Which will you say is natural, which is man made?

Which one will you say is which when shown a brand new Sony robot and a seventy year old human being? Why?

Which one will you say is which when you listen to the sounds of a thunderstorm and the sounds of a heavy metal music group from the 60's? Why?

You will be taken to a wildlife area and watch a lion hunt, kill, and eat his prey. Afterwards you will be taken to a war torn area where you will watch human beings kill each other. Which scene will you say is naturual? Why?

Finally, you will look at yourself in a mirror. Man made or natural?
Perhaps both?