USELESSNESS OF MERE ASSERTION. 225 



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 andparticulartheories, 

 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 

 a 



