xiii CLASSIFICATION 221 



standard by which we can judge of the accuracy of a 

 given classification, or does the whole thing depend 

 upon the fancy of the classifiers, like the arrangement 

 of books in a library ? In other words, are all possible 

 classifications of living things more or less artificial, 

 or is there such a thing as a natural classification ? 



.Suppose we were to try to classify all the members of 

 a given family parents and grandparents, uncles and 

 aunts, cousins, second cousins, and so on. Obviously 

 there are a hundred ways in which it would be possible 

 to arrange them into dark and fair, tall and short, 

 curly-haired and straight-haired, and so on. But it is 

 equally obvious that all these methods would be purely 

 artificial, and that the only natural way, i.e., the only 

 way to show the real connection of the various members 

 of the family with one another, would be to classify 

 them according to blood-relationship ; in other words, 

 to let our classification take the form of a genealogical 

 tree. 



There are two theories which attempt to account for 

 the existence of the innumerable species of living things 

 which inhabit our earth : the theory of special creation 

 and the theory of evolution. 



According to the theory of creation, all the individuals 

 of every species existing at the present day the tens of 

 thousands of dogs, frogs, oak-trees, and what not are 

 derived by a natural process of descent from a single 

 individual, or from a pair of individuals in each case 

 precisely resembling, in all essential respects, their 

 existing descendants which came into existence by a 

 process outside the ordinary course of nature and known 

 as creation. On this hypothesis each species of frog is 

 derived from a common ancestral pair which came into 

 existence, independently of the progenitors of all the 



