By that logic all technology is "natural" and there is no distinction between the inventions of man and the creations of nature/god. Such logic sidelines self reflection, leading to horrible places.
It is something I've read many times and get something new every time I read it. Given the context of this thread, I'm not sure I could recommend a more salient book.
Self-reflexion is the ultimate unnatural act which is (almost if not) completely unique to our species, and it's not to hard to argue not entirely ubiquitous within us.