26 Darwin, and after Darwin. 
that through all these changes of theory or principle, 
and through all the ever-advancing construction of 
their taxonomic science, naturalists themselves were 
unable to give any intelligible reason for the faith that 
was in them—or the faith that over and above the 
artificial classifications which were made for the mere 
purpose of cataloguing the living library of organic 
nature, there was deeply hidden in nature itself a truly 
natural classification, for the eventual discovery of 
which artificial systems might prove to be of more or 
Icss assistance. 
Linnzus, for example, expressly says—“You ask 
me for the characters of the natural orders ; I confess 
that I cannot give them.” Yet he maintains that, 
although he cannot define the characters, he knows, 
by a sort of naturalist’s instinct, what in a general way 
will subsequently be found to be the organs of most 
importance in the eventual grouping of plants under 
a natural system. “TI will not give my reasons for the 
distribution of the natural orders which I have pub- 
lished,” he said: “you, or some other person, after 
twenty or after fifty years, will discover them, and see 
that I was right.” 
Thus we perccive that in forming their provisional 
or artificial classifications, naturalists have been guided 
by an instinctive belief in some general principle of 
natural affinity, the character of which they have not 
been able to define; and that the structures which 
they selected as the bases of their classifications when 
these were consciously artificial, were selected because 
it seemed that they were the structures most likely to 
prove of use in subsequent attempts at working out the 
natural system. 
