Preface vii 
mental conceptions and the aims of the students of living Nature 
have been completely changed....But the impulse thus given to 
scientific thought rapidly spread beyond the ordinarily recognised 
limits of Biology. Psychology, Ethics, Cosmology were stirred to 
their foundations, and The Origin of Species proved itself to be the 
fixed point which the general doctrine needed in order to move the 
world.” 
In the contributions to this Memorial Volume, some of the authors 
have more especially concerned themselves with the results achieved 
by Darwin’s own work, while others pass in review the progress of 
research on lines which, though unknown or but little followed in his 
day, are the direct outcome of his work. 
The divergence of views among biologists in regard to the origin of 
Species and as to the most promising directions in which to seek for 
truth is illustrated by the different opinions of contributors. Whether 
Darwin’s views on the modus operandi of evolutionary forces receive 
further confirmation in the future, or whether they are materially 
modified, in no way affects the truth of the statement that, by employ- 
ing his life “in adding a little to Natural Science,” he revolutionised 
the world of thought. Darwin wrote in 1872 to Alfred Russel Wallace : 
“How grand is the onward rush of science: it is enough to console us 
for the many errors which we have committed, and for our efforts 
being overlaid and forgotten in the mass of new facts and new views 
which are daily turning up.” In the onward rush, it is easy for students 
convinced of the correctness of their own views and equally convinced 
of the falsity of those of their fellow-workers to forget the lessons of 
Darwin's life. In his autobiographical sketch, he tells us, “I have 
steadily endeavoured to keep my mind free so as to give up any 
hypothesis, however much beloved...as soon as facts are shown to be 
opposed to it.” Writing to Mr J. Scott, he says, “It is a golden rule, 
which I try to follow, to put every fact which is opposed to one’s 
preconceived opinion in the strongest light. Absolute accuracy is the 
hardest merit to attain, and the highest merit. Any deviation is 
ruin.” 
He acted strictly in accordance with his determination expressed 
in a letter to Lyell in 1844, “I shall keep out of controversy, and just 
ad 
