124 ON SYSTEMATIC ZOOLOGY. 
groups (that is to say, groups which the judgment im- 
mediately pronounces as not to be thoseof nature), while, 
in other respects, it may preserve the natural series. If, 
therefore, we were to rest content with this difference 
between a natural and an artificial system, we should 
have a difference without a distinction; both might be 
called natural, and both artificial ; the difference would 
only be in degree; and that degree would rest upon 
individual opinion, because, where there are no tixed 
principles by which the judgment in such matters is to 
be regulated, there could be no unanimity of opinion. 
Besides, it would inevitably follow, that our application 
of these terms to any given system would be subject to 
change. A system, which we would term natural in 
one state of the science, would be artificial in another ; 
sO soon as it was supplanted by more recent discoveries, 
and a more harmonious combination of objects. We 
must search, therefore, for a clearer definition of these 
two modes of arrangement. 
(177.) Much metaphysical discussion has arisen on 
the difference between natural and artificial systems, 
which has left the subject pretty nearly in the same un- 
decided state, while some of these discussions have rather 
increased than dissipated the obscurity in which it has 
been involved. Some maintain, that, as all systems 
hitherto promulgated are more or less defective, and 
have failed to reconcile and explain ali the intricacies 
of the natural series, therefore, they argue, all systems 
are, and must be, artificial. Mr. Macleay, in his con- 
troversy with Mr. Bicheno * on systems and methods, 
evidently embraces this view of the subject, and his 
opinion has been more recently taken up by one of his 
disciples. He asks: “ Pray let me know where J shall 
find one of these natural systems, and I shall be con- 
tent.” Again: ‘ Naturalists have been looking for 
one natural system, on/y one; and, confined as their aim 
is, they have not as yet been able to attain it?”’+ What 
* Zool. Journ. vol. iv. p. 409. + Ibid. p. 410. 
