io MIND IN EVOLUTION CHAP. 



securing a meal. But purpose as a conscious process in 

 the cat has no causal efficacy. What works is the physical 

 system, and we ought to attribute to this system not the 

 fulfilment of a purpose but the performance of a function 

 in the life of the cat. Indeed, according to one theory all 

 actions of living beings from the pounce of the cat to the 

 inventions of the engineer or the creations of the poet 

 are in the last resort to be explained in this fashion. All 

 are the reactions, highly specialised it may be, but still the 

 reactions of a complicated machine. If we keep to the 

 facts, however, we recognise great differences of type in 

 the behaviour not only of men but of animals. Some 

 forms of behaviour conform to the mechanical type. They 

 serve a function, but in doing so they proceed with 

 a machine-like uniformity. Others bear no resemblance 

 to machine-processes, and the more closely we analyse 

 them the more definite does the difference become, and 

 these are the modes of behaviour usually attributed 

 to Mind. Now whether this distinction is fundamental 

 or superficial, whether the apparent independence of Mind 

 is an illusion or a reality, how the relations between the 

 mental and the physical are to be understood are philo- 

 sophical questions which we can only approach with any 

 advantage when we have all the apparent differences before 

 us. But that there are differences between forms of 

 behaviour, and in particular differences in the kind and 

 degree of correlation that they exhibit is, as we shall argue 

 in the next chapter, simple matter of fact. Our main 

 object in this volume is to exhibit these differences, 

 to distinguish the principal types of correlation that are 

 found in the behaviour of living beings. These will be 

 found to range themselves under the two great classes of 

 the mechanical and the mental. Even if ultimate analysis 

 should resolve one of these into the other or both into a 

 more ultimate unity, within that unity the distinction 

 would still hold. There would still be specific differences 

 in correlation of the highest significance for the evolution 

 I of life. In particular we shall see that the kind of corre- 

 1 lation which we attribute to Mind is wider in scope and 

 * more complete in the detail of its adjustment than that 



