128 TILE DOCTRINE OF DESCENT. 
theory makes its way affords the best evidence that it 
took shape and was proclaimed at the proper moment. 
That the doctrine of Descent was likewise no utterly 
startling apparition, even though it leapt forth from the 
head of Darwin, its greatest representative, like an armed 
Minerva—of this we have cited at least a few of the many 
vouchers. ‘That its time had come,—that it was indeed 
more than time, unless the science of the nature of life, 
and Biology in general, was to be unduly backward,— 
is shown by the development of Geology, which thirty 
years prior to Darwin, after many favourable forecasts, 
struck upon the right road to the knowledge of causes. 
The doctrine of the formation and evolution of the 
earth, especially in its earlier phases, during which Life, 
in the sense generally attached to the word, originated 
and became permanent on our Planet,—this science of 
Geology is intimately allied with our important theme. 
Modern Geology, especially as connected with the name 
of Charles Lyell, must sooner or later have necessitated 
an analogous treatment of vegetal and animal lore, and 
we can only wonder that the crisis was so long delayed. 
The exposition of the doctrine of Descent must, there- 
fore, be introduced and initiated by a reference, however 
brief, to modern Geology. 
The first edition of Lyell’s “Principles of Geology” 
appeared in 1830. The tenth, published in 1866, gave him 
an opportunity of professing his full adhesion to the 
Darwinian doctrines, to the development of which he 
had given so great an impulse. Since 1872, the eleventh 
edition of this masterpiece has been before the world. 
It treats of the investigation of the lasting effects of 
causcs now in operation, as data from which inferences 
