One of the problems of exploring an intellectual discipline from the outside is that the importance of certain basic methodological considerations is not always apparent to the observer, considerations that mold the entire intellectual structure that characterizes the field. So, in her first chapter, “Nature and Nurture as Alternatives,” Fox Keller writes that “my concern is with the tendency to think of nature and nurture as separable and hence as comparable, as forces to which relative strength can be assigned.” That concern is entirely appropriate for an external critic, and especially one who, like Fox Keller, comes from theoretical physics rather than experimental biology. Experimental geneticists, however, find environmental effects a serious distraction from the study of genetic and molecular mechanisms that are at the center of their interest, so they do their best to work with cases in which environmental effects are at a minimum or in which those effects can be manipulated at will. If the machine model of organisms that underlies our entire approach to the study of biology is to work for us, we must restrict our objects of study to those in which we can observe and manipulate all the gears and levers