USELESSNESS OF MERE ASSERTION. 995 
theory which explains these, must be considered 
as demonstrably true. Let the advocates for any 
determinate number, instead of declaiming in ge- 
neral terms in favour of their own opinion, and in 
abuse of others, throw aside such puerilities, as un- 
worthy the name either of argument or of science ; 
let them in good earnest put their shoulders to the 
wheel, and resolutely sit down to study and de- 
velope the natural arrangement of any one of the 
groups just named: we shall then have a standard 
to which all parties can appeal; we shall then see, 
beyond dispute, whether, in one of the most perfect 
groups in creation, nature has, or has not, regulated 
the variation of her forms by some definite number, 
or by some definite rule. It is a matter of perfect 
indifference to the man of true science whether that 
number be three, five, seven, or twenty. We want 
truth, and truth only ; and all that is true in physical 
science must repose on the experience or observation 
of facts within the reach of those who seek for them. 
One such analysis as we are now recommending, 
would tend more to the establishment of sound 
principles in natural history, than all the speculative 
declamation that was, or will be, ever written. It is 
surely not too much to expect such labour, —for 
labour it will assuredly prove,—from those who 
declaim against general views and particulartheories, 
before they have informed themselves on the very 
first rules of judging which physical science imposes 
upon her votaries. Let us return, however, to the 
more immediate subject before us, viz. the verifi- 
cation of natural groups. 
(157.) We have, in the last paragraph, spoken 
Q 
