388 DIFFICULTY OF DEFINING chap. XX. 



arguments of the transmutationist, who contends that all 

 closely allied species of animals and plants have in like 

 manner sprung from a common parentage, albeit that for 

 the last three or four thousand years they may have been 

 persistent in character? Where are we to stop, unless we 

 make our stand at once on the independent creation of those 

 distinct human races, the history of which is better known 

 to us than that of any of the inferior animals ? 



So long as Geology had not lifted up a part of the veil 

 which formerly concealed from the naturalist the history of 

 the changes which the animate creation had undergone in 

 times immediately antecedent to the Eecent period, it was 

 easy to treat these questions as too transcendental, or as 

 lying too far beyond the domain of positive science, to 

 require serious discussion. But it is no longer possible to 

 restrain curiosity from attempting to piy into the relations 

 which connect the present state of the animal and vegetable 

 worlds, as well as of the various races of mankind, with the 

 state of the fauna and flora which immediately preceded. 



In the very outset of the inquirj', we are met with the 

 difficulty of defining what we mean by the terms "species" and 

 *'race;" and the surprise of the unlearned is usuall}' great, 

 when they discover how wide is the difference of opinion now 

 prevailing as to the significance of words in such familiar 

 use. But, in truth, we can come to no agreement as to such 

 definitions, unless we have previously made up our minds on 

 some of the most momentous of all the enigmas with which 

 the human intellect ever attempted to grapple. 



It is now thirty years since I gave an analysis in the first 

 edition of my "Principles of Geology" (vol. ii. 1832) of the 

 views which had been put forth by Lamarck, in the be- 

 ginning of the century, on this subject. In that interval 

 the progress made in zoology and botanj^, both in aug- 

 menting the number of known animals and plants, and in 



