The first question that anyone asks when encountering an unfamiliar plant or creature is ‘What is it?’. Somehow we feel happier once we can call the ‘thing’ by a name. Perhaps this relates to our pattern of language development: no young child is content until it has a name with which to refer to anything it sees. Rapidly, and unthinkingly, we come to know the degree of variation acceptable within the category ‘cat’, for example, before it comes something else or a subdivision of the ‘cat’ group (my cat). We are born taxonomists.