83 THE DOCTRINE OF DESCENT. 
These phrases are interchangeable, but, like all dogma- 
tism, they make a great impression on those who from 
ignorance of the facts are incapable of criticising for 
themselves, and they are readily quoted to confute an 
unbelieving investigation of nature by one made in 
faith. 
It might be thought that if the affair were so simple, 
and systematic ideas so firmly fixed, nothing would be 
easier than to establish the system. And so Agassiz 
maintains. He says that if a single species of any of 
the great animal groups were present, and admitted of 
investigation, the character of the type, class, family, 
genus, and species, might be determined. The weak- 
ness of this and similar statements may best be demon- 
strated by examining the basis of all dogmatic system, 
—the “ species.” If this idea be mutable, if the species 
be not given once for all, but variable, according to 
time and circumstances, the implications of the higher 
ahd more general ideas of genus, family, &c., must 
necessarily ensue. The keenest and most logical criti- 
cism on the deeply-rooted scholastic idea of “species” 
was made by Haeckel,” after Darwin, in his classical 
work on the “Origin of Species,’ had completely ex- 
posed the old doctrine and practice of zoology and 
botany. In what follows we shall adhere to Haeckel. 
We have seen above that Linnzeus accepted the Crea- 
tion as an irrevocable scriptural doctrine, and it is really 
absurd that many naturalists who have long abandoned 
any other dogma, should abide by this one.. Therefore 
as the Bible mentions the creation of species, this legend 
was made the basis of all science. It is true there are 
not now many who appeal to scriptural testimony, 
