88 SECTIONAL ADDRESSES 
select from the panorama of objective appearance those facts which are 
of interest from our own particular point of view, and so to devise our 
researches as to obtain answers to problems which we impose upon Nature 
rather than Nature upon us. 
Thus if we are firmly convinced that all events are ruled by strict 
mechanical causality we naturally look upon the organism as a machine, 
and when we study the behaviour of an animal we seek to analyse it into 
a number of simple constituents, such as tropisms and reflexes, which are 
determined by simple and measurable external stimuli. We lean in- 
evitably towards the stimulus-response theory of behaviour—a purely 
physiological and analytical view—and our researches are based on the 
supposition that this theory is true. Hence we tend to overlook facts 
which do not fit into this scheme—we miss them simply because we are 
not looking for them. 
The point I want to get clear is that the Cartesian doctrine of the 
dualism of matter and mind is in no sense an inevitable deduction from 
experience ; one is not forced to accept it as the necessary foundation of 
biological research ; other foundations are possible, as we shall see in 
a moment. 
I have in my preceding remarks purposely exaggerated to some degree 
the contrast between the physiological and the psychological attitude 
towards the study of animal behaviour, in order to bring out clearly the 
logical consequences of accepting the metaphysical theory of the dualism 
of matter and mind. But I do not mean to assert that all work on animal 
behaviour can be definitely labelled either as physiology or as psychology 
in this limited sense. An escape from the dilemma has in practice been 
found, and this alternative method we shall now proceed to discuss. 
Let us first of all try to rid our minds of the abstract notions of matter 
and mind, and regard the activities of living things without metaphysical 
preconceptions. As zoologists our job is to study animals in action. 
Let us try to approach our task with the same directness and naiveté that 
Aristotle showed when he laid the foundations of our science. Instead 
of assuming a priori that the physico-chemical or analytical method of 
approach is the only possible and the only fruitful one, let us try the 
alternative of considering first the most general characteristics of the 
organism as a whole, and working down from the whole to the parts, 
rather than up from the parts to the whole, as is the more usual method. 
Taking this simple and direct view of living things, abandoning theory 
and accepting the obvious facts at their face value, we see first of all that 
the complete phenomena of life are shown only by individuals, or organised 
unities. Sometimes these units are combined loosely or closely in unities 
of higher order, as in social insects and in colonial animals, such as corals, 
but these cases hardly affect the main thesis that life is a function of 
individuals. There is accordingly no such thing as ‘ living matter,’ save 
as part of an organised unity. 
The second thing we note is that all living things pass through a cycle 
of activity, which normally comprises development, reproduction, and 
senescent processes leading to death. This life-cycle is in each species a 
