94 GENERAL CONSIDERATIONS RESPECTING THE 



To return to a consideration of the positive arguments for 

 an organic creation by law, we have seen that this stands in 

 harmony with our conclusions as to the cosmical arrangements, 

 and also those regarding the geognostic changes. We are 

 now to observe that it consorts equally well with what we 

 know of the actual history of organic beings upon the earth. 

 These came not at once, as they might have been expected to 

 do if produced by some special act, or even some special inter- 

 position of will, on the part of the Deity. They came in a 

 long-extending succession, in the order, as we shall afterwards 

 see more convincingly, of progressive organization; grade 

 following grade, till, from a humble starting-point in both 

 kingdoms, the highest forms were realized. Time, we see, 

 was an element in the evolution of Being, as it is in the repro- 

 duction of an individual at the present day. At the beginning 

 of geological investigation, it was thought that some imme- 

 diate external conditions ruled the appearance of particular 

 classes of animals at particular times : as that the absence of 

 dry land was the cause of the late commencement of terrestrial 

 animals; that there being for a long time only reptilian land 

 vertebrata was owing to an overcharge of the atmosphere with 

 carbonic acid the store from which came the chief material 

 of the abundant vegetation of the carbonigenous age ; and so 

 forth. But it is now seen that the progress of the animal 

 world was, in its main features, independent of such circum- 

 stances. There was dry land unreckonable ages before there 

 were any land animals. The sea abounded in invertebrate 

 animals before there were any fish, though the conditions 

 required for the existence of both are the same. The oolitic 

 continents where only reptiles roamed could have equally 

 supported mammalia, for which the atmosphere was then fully 

 fitted, even upon the admission of the carbonic acid theory, 

 as the coal was by that time formed; yet mammalia came 

 not. It was also a dream at the dawn of true geology, that 

 fresh creations of animals were connected with great physical 

 revolutions of the surface ; as if, at particular times, all had 

 perished in storms of volcanic violence, and been replaced with 

 a wholly new fauna. But this idea is likewise passing away. 



