2 THE PRESIDENTIAL ADDRESS 
and to make ‘an investigation of the permanent effects of causes 
now in action which may serve as records to after ages of the present 
condition of the earth and its inhabitants.’ By laborious study of 
the work of others, and by his own extensive travel and research, he 
had been able to enunciate, for the inorganic world, the principle 
of uniformitarianism, which in its original form we owe to Hutton. 
This principle involved that the history revealed by the rocks 
should be read as the effect of the slow but continuous operation of 
causes, most of them small, such as could be seen in action in some 
part or other of the world to-day. ‘This was set in opposition to the 
opinion of the older geologists who had postulated a succession of 
catastrophes which, by flood, fire and convulsion, had periodically 
wrecked the world and destroyed its inhabitants ; each catastrophe 
necessitating a new creation to provide the succession of life on the 
earth as it then was known. 
But in the organic world Lyell, like Hutton, had failed to detect 
any analogous principle, and, as he rejected all the theories of 
transmutation of species then in vogue, he had to accept their 
absolute fixity ; and to suppose that, as species became extinct one 
after another, replacement by special creations followed. And yet 
the reading to-day of the chapters devoted to this branch in the 
earlier editions of Lyell’s great work produces the haunting feeling 
that a better explanation had only just eluded him. It was the 
story revealed in Lyell’s work, Darwin tells us, the new conception 
that the earth had been in existence for vast zons of time, the proof 
that it had been continuously peopled by animals and plants, and 
that these had steadfastly advanced and improved throughout that 
time, which showed him the necessity for an explanation of the 
progression of life, and gave him the first hints of his theory. When 
he had enunciated this he was enabled to repay his master with the 
principle of organic evolution, which brought changes in the animate 
world into harmony with those of the inanimate. 
His Antiquity of Man shows that by 1863 Lyell had become a 
convert, and he afterwards rewrote much of the second volume 
of his Principles accepting the new point of view. This change 
earned from Hooker a testimonial in the 1868 address which, if not 
unique, must certainly be one of the most magnificent ever awarded 
to a scientific work : 
‘I know no brighter example of heroism, of its kind, than this, 
of an author thus abandoning, late in life, a theory which he 
had regarded as one of the foundation stones of a work that had 
given him the highest position attainable amongst contemporary 
scientific writers. Well may he be proud of a superstructure, 
raised on the foundation of an insecure doctrine, when he finds 
