THE LEVELS OF BEHAVIOUR 139 



by assimilation, so much of the parts of its body that undergo 

 waste by reason of their own activities. This organic process is, 

 in a way, the opposite of the degradative and dissipative process 

 that tends to the destruction of the animal system. The latter 

 maintains its " normality " and that maintenance is the result 

 of the life-urges — it expresses life. 



The activities that maintain normality need not be conscious 

 ones. We have no reason to believe that the suckling infant has 

 '' knowledge " of the complex activities that it carries out. We 

 are unconscious of assimilation, or growth, but " purpose," in 

 the sense of tendency that is opposite to the purely physical ones 

 of tissue katabolism, underlies such functioning. It is in this 

 sense that we may speak of the purpose of the processes that 

 maintain an *' artificial " tissue-culture. The purposes may not 

 be such as to warrant our ascribing consciousness to the systems 

 in which they are manifested, but they must be assumed and 

 regarded as something that is, in the wider sense, psychical. 



IV. THE LEVELS OF BEHAVIOUR 



The motions of animals that we call their behaviour are there- 

 fore to be considered as the manifestations of urges, psychical 

 in nature, though they may not rise into consciousness, and 

 having " purpose " in the sense that they are tendential in a 

 direction in which a material-energetic system as such, is not 

 tendential. They operate so as to confer power over the imme- 

 diate environment. We can consider the behaviours of all 

 animals in these terms. But there are many general types of 

 animal structure and innumerable variations of these general 

 types. So also there are as many types and variations, or 

 patterns of behaviour. We shall, quite arbitrarily but con- 

 veniently, consider these patterns as falling into various rough 

 levels or grades of complexity. In the more complex grade the 

 behaviour is the more efficient, in the sense that it confers on the 

 animal exhibiting it all the more power over its environment. 



50. ON THE INORGANIC MODEL— SIMPLE RESPONSE 

 Let there be a compass needle freely movable on its pivot in 

 a magnetic field. The latter may be that established in the 

 neighbourhood of a bar magnet which can be moved in position. 



