THE LAW OF EVOLUTION. 333 



of like entities and like relations, may be said to constitute 

 the most conspicuous part of scientific progress. A glance 

 at the classificatory sciences, shows us that the confused 

 incoherent aggregations which the vulgar make of natural 

 objects, are gradually rendered complete and compact, and 

 bound up into groups within groups. While, instead of 

 considering all marine creatures as fish, shell-fish, and jelly- 

 fish, Zoology establishes divisions and sub-divisions under 

 the heads Vertebrata,Annulosa, Mollusca, &c. ; and while, 

 in place of the wide and vague assemblage popularly de- 

 scribed as " creeping things," it makes the specific classes 

 Annelida, Myriopoda, Insecta, Arachnida ; it simultaneous- 

 ly gives to these an increasing consolidation. The several 

 orders and genera of which each consists, are arranged ac- 

 cording to their affinities and tied together under common 

 definitions; at the same time that, by extended observation 

 and rigorous criticism, the previously unknown and un- 

 determined forms are integrated with their respective con- 

 geners. Nor is the process less clearly manifested 

 in those sciences wnich have for their subject-matter, not 

 classified objects but classified relations. Under one of its 

 chief aspects, scientific advance is the advance of generaliza- 

 tion; and generalizing is uniting into groups all like co- 

 existences and sequences among phenomena. The colliga- 

 tion of many concrete relations into a generalization of 

 the lowest order, exemplifies this principle in its simplest 

 form; and it is again exemplified in a more complex form 

 by the colligation of these lowest generalizations into 

 higher ones, and these into still higher ones. Year by year 

 are established certain connexions among orders of phe- 

 nomena that appear unallied; and these connexions, multi- 

 plying and strengthening, gradually bring the seemingly 

 unallied orders under a common bond. "When, for example, 

 Humboldt quotes the saying of the Swiss " it is going to 

 rain because we hear the murmur of the torrents nearer," 

 when he remarks the relation between this and an observa- 



