St. Thomas Aquinas is generally seen as having an anthropocentric and instrumentalist view of nature, in which the rational human is the point of the universe for which all else was created. I argue that, to the contrary, his metaphysics is consistent with a holistic ecophilosophy. His views that natural things have intrinsic value and that the world is an organic unity in which diversity is itself a value requiringrespect for being and life in all their manifestations.