  The significance of this observation resides in the thought that any adequate account of nutrition will make ineliminable reference to life as such. This in turn entails that it will not be possible to define life as the capacity for taking on nutrition. For then we would have a vicious circularity: a living system is the sort of thing which can take on nutrition, while nutrition is whatever stuff is such as to sustain a living system. So, if living systems cannot be reductively defined in some other way, it will follow that no reductive account of life will be forthcoming. Consequently, Aristotle’s discussion of nutrition provides some reason for thinking that he will resist any attempt to define life in terms which do not themselves implicitly appeal to life itself. That is, he will resist any reductive account of life.