PRINCIPLES 0V SCIENTIFIC ARRANGEMENT. 121 



ORDERS, CLASSES, FAMILIES, and GENERA, all deduced 

 in their successive and collateral groups from characters 

 exclusively derived from SPECIES; therefore to the accu- 

 rate knowledge of species all endeavours must be directed, 

 they comprising within themselves all the rest, although 

 the characters upon which they themselves depend for 

 separation from their congeners are the most trivial of 

 any. Each combination, in its analytical descent, con- 

 tains characters of wider compass than those which suc- 

 ceed it, and consequently embraces in that descent more 

 species than the successive divisions ; just as in the ascent, 

 or synthetical method, the characters of every successive 

 group gradually expand. Species being thus the only 

 real objects in nature from which all knowledge springs, 

 and in which exclusively all uses lie, other combinations 

 being perhaps as merely imaginary as are the many 

 lines which are drawn over the surface of the globes, it 

 would imply that subdivisions merely lend aid to ac- 

 quire more rapidly the details upon which they depend. 

 A^e will, therefore, first turn our attention to species. 



Both combination and subdivision are intended to 

 facilitate identification, by aiding us to arrive at this 

 knowledge of species ; for each species represents a dis- 

 tinct idea, whose correct definition is important to the 

 progress of accurate science. This alone permits ob- 

 servation to be attributed to its right object, and when 

 properly recorded, the information is secured for ever 

 from error or obscurity. It is not, however, the gift of 

 every mind to discern accurately even specific differences, 

 or to form skilfully generic combinations. The very best 

 favoured by nature, for it is a natural gift, although 

 under high cultivation, have sometimes a bias towards 

 seeing more than actually exists. Hence varieties are 



