438 OPERATIONS SUBSIDIARY TO INDUCTION. 



has stated very clearly and forcibly, but (I think) without making all 

 necessary distinctions, one of the principles of a Natural Classification. 

 What this principle is, what are its limits, and in what manner Mr. 

 Whewell seems to me to have overstepped them, will appear when 

 we have laid down another and more fundamental rule of Natural 

 Arrangement, entitled to precedency over that which Mr. Whewell 

 has here in view. 



§ 4. The reader is by this tiine familiar with the general truth 

 (which I restate so often on account of the great confusion in which it 

 is commonly involved), that there are in nature distinctions of Kind ; 

 distinctions not consisting in a given number of definite properties, 

 fhis the effects which follow from those properties, but running through 

 the whole nature, through the attributes generally, of the things so 

 distinguished. Our knowledge of the properties of a Kind is never 

 complete. We are always discovering, and expecting to discover, 

 new ones. Where the distinction between things is not one of kind, 

 we expect to find their properties alike, except where there is some 

 reason for their being different. On the contrary, when the distinction 

 is in kind, we expect to find the projjerties different unless there be 

 some cause for their being the same. All knowledge of a Kind must 

 be obtained by observation and experiment upon the Kind itself; no 

 inference respecting its properties from the properties of things not 

 connected with it by kind, goes for more than the sort of presumption 

 usually characterized as an analogy, and generally in one of its faint.er 

 degrees. 



Since the common properties of a true Kind, and consequently the 

 general assertions which can be made respecting it, or which are cer- 

 tain to be made hereafter as our knowledge extends, are indefinite and 

 inexhaustible ; and since the very first principle of natural classification 

 is that of forming the classes so that the objects composing each may 

 have the gi'eatest number of properties in common ; this principle 

 prescribes that every such classification shall recognize and adopt into 

 itself all distinctions of Kind, which exist among the objects it pro- 

 fesses to classify. To pass over any distinctions of Kind, and substitute 

 definite distinctions, which, however considerable they may be, do not 

 point to ulterior unknown differences, would be to replace classes with 

 more by classes with fewer attributes in common ; and would be sub- 

 versive of the Natural Method of Classification. 



Accordingly all natural arrangerrients, whether the reality of the 

 distinction of Kinds was felt or not by their framers, have been led, by 

 the mere pursuit of their own proper end, to conform themselves to 

 the distinctions of Kind, so far as these had been ascertained at the 

 time. The Species of Plants are not only real Kinds, but are prob- 

 ably,* all of them, real lowest Kinds, or Infimas Species ; which if we 

 were to subdivide, as of course it is open to us to do, into sub-classes, 



* I say probably, not certainly, because tliis is not the consideration by which a botanist 

 determines what shall or shall not be admitted as a species. In natural history those 

 objects belong to the same species, which are, or consistently with experience might have 

 been, produced from the same stock. But tliis distinction in most, and probably in all 

 cases, happily accords with the other. It seems to be a law of physiology, that animals 

 and plants do really, in the philosophical as well as the popular sense, propagate their kind ; 

 transmitting to their descendants all the distinctions qf Kind (down to the most special 0? 

 lowest Kind), which they themselves 



