THE VITAL IMPETUS 155 



and adequate one and we shall adopt it. The physical 

 stimulus, then, leads to a state of consciousness, a 

 perception, and this is succeeded by the action. What 

 is the perception ? There may be no perception in a 

 reflex action ; there is none in a taxis. 1 These kinds of 

 reaction follow inevitably from the nature of the 

 stimulus depend upon the latter, in fact ; but we 

 cannot fail to observe that the intelligent behaviour 

 of the higher animal involves choice between alternative 

 kinds of action. The perception, then, is this choice, 

 or it is intimately associated with it. But it is some- 

 thing more than the choice of one among many kinds 

 of response. The whole past experience of the animal 

 enters into the perception, or at least all that part of 

 the past experience which illuminates, in any way, 

 the present situation. What the intelligent animal 

 does in response to a stimulus depends not only on 

 the stimulus but on all the stimuli that it has received 

 in its past, and on all the effects of all those stimuli. 

 Into the perception that intervenes between the external 

 stimulus, then, and the action by which the animal 

 responds what we usually call its memory enters. Its 

 duration is really the something which is changed by 

 the stimulus, and which then leads to the behaviour- 

 reaction. 



Duration, then, is* memory, but it is more than 

 memory as we usually think of this quality. The past 

 endures in us in the form of " motor habits," and when 

 we recall it we may act over again those motor events. 

 Careful introspection will readily convince the reader 

 that in recalling a conversation he is really speaking 

 inaitdibly, setting in motion the nerves and muscles 



1 We do not find this explicitly stated in this way in mechanistic biological 

 writings. None the less it is implied, and is the legitimate conclusion from 

 the arguments used. 



