84 SECTIONAL ADDRESSES 
ecology. Its head is Professor of Natural History, and both the present 
occupant and his predecessor, the late Sir John Arthur Thomson—to 
whom I personally owe so much—have made great contributions to the 
study of that subject which Prof. W. M. Wheeler has so aptly called ‘ the 
perennial root-stock or stolon of biological science.’ 
Interest in natural history is—fortunately—still widespread among 
zoologists, both professional and amateur, and one of the most significant 
developments of recent years has been the vigorous growth of the 
Oxford school of animal ecologists, under the leadership of Mr. Charles 
Elton. 
But while excellent work in the field of scientific natural history is 
being done by the animal ecologist, the economic entomologist, the 
fishery worker and also by the amateur naturalist, they have not as a rule 
taken what one might call a professional interest in the problems of 
animal behaviour, though they have accumulated a great store of observa- 
tions which are df the highest value to the professional student. 
Generally speaking, as things are at present, the study of animal 
behaviour as a science has not in this country taken its rightful place as 
an essential part of zoology, either in research or in teaching; the 
tendency has been to treat it either as a branch of physiology or as an 
adjunct to psychology, and in both cases to turn it into a laboratory 
subject. 
When we inquire into the reasons for this unsatisfactory state of affairs, 
we find, I think, that one of the main causes is the influence upon biology 
of a certain metaphysical theory which we inherit from the seventeenth 
century. We owe to the great thinkers of that age, and particularly to 
Descartes, a particular view about the nature of reality which has become 
firmly rooted in our thought and is apt to bias our methods of research. 
I refer of course to the classical doctrine of materialism, with its absolute 
separation of matter and mind. 
How did this doctrine arise? We do not find it in Aristotle. The 
dualism of matter and mind was foreign to his thought. A primitive 
form of materialism had been propounded by the Ionians, and Anaxagoras 
had added to their cosmology the conception of a universal reason or 
‘Nous.’ But Aristotle accepted neither view. He worked out a system 
of his own, which is now somewhat difficult for us to grasp, for we have 
lost that freshness and directness of approach to the great problems 
which were his. We know that he spoke of the nutritive, the sensitive 
and the rational ‘ souls,’ which formed a hierarchy of functions, but, with 
the possible exception of the rational soul, he did not think of these as 
separate from the body. His view was not vitalistic in the modern 
sense ; it did not imply a dualism of matter and entelechy ; for Aristotle, 
“soul ’ was an expression for the total functional activity of the organic 
unit, for its activity as a whole. ; 
We do not find the clear-cut dualism of matter as extended substance 
and mind as inextended thought fully expressed until we come to 
Descartes many centuries later. 
Descartes stands on the threshold of the modern world. No man can 
