How do we define life – or, in fact, can it be defined? So far, we cannot be sure that this question has been properly answered. Even so, NASA has proposed that life be taken as a self-sustained chemical system capable of undergoing Darwinian evolution. If we have a mind for science, we might then ask – is this consistent with basic principles? The life chemistry we find on Earth should accord with this, but as one particular case. This point of view can then allow us to seek for life in other places –“space” – say, but on the basis of rational enquiry.