'We may think we know what “life” is, or means, at a literal level. But, in general, definitions of “life” boil down to oppositions between “life” and “non-life” — circular arguments that never seek to specify the boundary between the two. For example: If life exists in a given entity, can parts of that entity be alive in their own right? “It would be wrong to say that the molecules in an organism are living things, but it isn’t a stretch to say that the gross organs that compose a body are themselves living things”'