I quote Jacob Ghitis in his reply to a similar question.
Being ourselves a result of the Physical Laws, which determine how energy-matter interact, we are as part of Nature as anything else created by those Laws. The only things that are not intrinsic to Nature are the things that we humans create using our minds and hands, feet, or mouths, be them a chair, a painting, a poem. Because those things are created by us, human beings, being, therefore, artificial. Yet, natural does not mean created by Nature, but being part of Nature, as a result of the ongoing effects of the physical laws, starting from the moment of the Big Bang. Thus, we --or anything else that exists naturally-- are part of Nature, not its creation. Nature does not create, it is continuously being created. Suppose a child grows in a desert, and he has no opportunity to see anything else, including any images of other places. He will come to the conclusion that Nature is mostly sand.
My intention has been to call the attention to the real signification of the name and concept of Nature.