J. Baird Callicott questions the basic premise of Lynn White Jr.’s essay “The Historical Roots of our Ecological Crisis,” where White attributes the environmental crisis to Genesis where God created man in his image, gave man dominion over the rest of creation, and commands him to subdue the Earth. Callicott examines White’s very epistemic assumption: that what we do depends on what we think. On this reckoning, we need to rethink the nature of nature, human nature, and the relationship between humans and nature in order to save the world from ecological disaster. But Callicott reminds us that the Lynn White Jr. of Medieval Technology and Social Change (1962) also proposes a theory of technological determinism to explain the fate of the West. So which is it? Is the mechanistic worldview of Descartes and Newton the product of Christian theology or mechanical technologies? Perhaps nature is more affected by things than ideas. If so, environmental philosophers have to give up the pretense that they alone can save the world from environmental destruction because they alone are expert at uncovering underlying conceptual presuppositions. Revolutionary developments in real material things are just as important as revolutionary ideas.