Theories of human nature are varied throughout history and across academic disciplines. The various theories of human nature help us to define the concept as it relates to nature, such as the definition of orignal sin and its external effects on human behavior. Sir Francis Bacon's interpretation of human nature challenges our ability to dominate over physical nature; and even, as one critic has said, "degrades and makes possible the exploitation of the natural environment." On the other hand, Rousseau places nature at the center of human nature by immersing himself in it both physically and mentally, as a means of achieving harmony within it. The contrasting theories of Bacon and Rousseau provide an interesting look at the concept of human nature.