Taking up such questions as what it means to be wild, what are the rights of animals introduced into an ecosystem compared to those already there, what steps are morally justifiable to take in the preservation of any given species when such actions may harm other species, and even if any animals are truly wild any longer given how much we humans have altered the world so as better for it to suit our own needs, Ms. Marris leads her readers into some of the most challenging philosophical questions surrounding conservation biology and its practices.