(0.28) 
down in the clear, calm, and simple language which did so 
much to convince an unwilling world. 
Darwin is speaking of the revolution which the acceptance 
of his views will bring about. “Systematists will be able to 
pursue their labours as at present; but they will not be 
incessantly haunted by the shadowy doubt whether this or 
that form be in essence a species. This, I feel sure, and I 
speak after experience, will be no slight relief. The endless 
disputes whether or not some fifty species of British brambles 
are true species will cease. Systematists will have only to 
decide (not that this will be easy) whether any form be suffici- 
ently constant and distinct from other forms to be capable of 
definition, and if definable, whether the differences be sufficiently 
important to deserve a specific name. This latter point will 
become a far more essential consideration than it is at present ; 
for differences, however slight, between any two forms, if not 
blended by intermediate gradations, are looked at by most 
naturalists as sufficient to raise both forms to the rank of 
species. Hereafter we shall be compelled to acknowledge that 
the only distinction between species and well-marked varieties is, 
that the latter are known, or believed, to be connected at the 
present day by intermediate gradations, whereas species were 
formerly thus connected. Hence, without quite rejecting the 
consideration of the present existence of intermediate grada- 
tions between any two forms, we shall be led to weigh more 
carefully, and to value higher, the actual amount of difference 
between them. It is quite possible that forms now generally 
acknowledged to be merely varieties may hereafter be thought 
worthy of specific names, as with the primrose and cowslip ; 
and in this case scientific and common language will come 
into accordance. In short, we shall have to treat species in 
the same manner as those naturalists treat genera, who admit 
that genera are merely artificial combinations made for con- 
venience. This may not be a cheering prospect, but we shall 
at least be freed from the vain search for the undiscovered 
and undiscoverable essence of the term species.” I have 
quoted from pages 484, 485 of the original edition (1859), 
and have italicised the sentences in which Darwin defines a 
species and distinguishes it from a variety. 
