44 INTRODUCTION. 
parents in their turn ; and some of their descendants, immediate 
or remote, may again differ among themselves ; diverging still 
farther from the original stock, either by increase in the first 
variation, or by other variations superadded thereto. Let such a 
process continue for an indefinite time, and through an indefinite 
number of generations, and the divergent variations from the 
original stock may (it is fancied) accumulate to any conceivable 
extent. Given, the measureless time; given, the countless gene- 
rations; given, the variations gradually increasing in kind and in 
number ;— all the differences now seen between the present 
species, and all the differences ascertained between the living and 
the extinct species, might thus have accumulated by way of 
repeated divergences from the original stock, whether single or 
sparingly multiple at first. 
So far, many other naturalists had held views closely similar to 
those lately announced by Mr. Darwin. Among animals and 
plants they have seen variations arise, and augment, and accumu- 
late, until some of the descendants have thus gradually become 
widely unlike their ancestors, certainly known or fairly supposed 
to be such. And they have thought and argued, if such changes 
can be seen produced in course of a human life or of human 
history ;— then, why not all the changes which geology shows to 
have occurred between the former and the present, the extinct and 
the living, animals and plants of the globe? During time so vast 
and measureless, these wide changes may also possibly have come 
to pass, as gradual evolutions of life in the ordinary course of 
nature. The result, as now seen or known, may perhaps have 
been practically and methodically brought about without the 
necessity of any direct interference of Creative Power, whether it 
be supposed to have been exerted immensely at some few distant 
intervals of time, or to be exerted very gradually and continuously 
through past and present time. All undoubtedly fore-seen and 
fore-arranged ; but fore-arranged with such perfect fore-sight, that 
no man-like intermeddling or rectifying could ever have become 
requisite. 
Sir Humphrey Davy, with others of his day and school, 
