AS ACCOMPANIMENT OF ORGANIC CHANGES 43 
say, on these grounds, whether it is a sentient animal or only 
an unconscious automaton ; and if it continued to behave in 
a similar fashion throughout life, our difficulty would still 
remain. But when we see that some objects are rejected 
while others are selected, we infer that consciousness in some 
way guides its behaviour. The chick has profited by experience. 
But even this is clearly only a criterion of what we may term 
effective consciousness. There may be sentience which is 
merely an accompaniment of organic action without any 
cuiding influence on subsequent modes of behaviour. In that 
case it is not effective; and whether it is present or not we 
have no means of ascertaining. 
We seem also to be led to the conclusion, both from a 
priori considerations and from the results of observation, that 
effective consciousness is associated with a nervous system. 
Its fundamental characteristic is control over the actions, so 
that some kinds of behaviour may be carried out with increased 
vigour, and others checked. And it is difficult to see how this 
can take place unless the centres of control are different from 
those over which they exercise this influence. If we are to 
understand anything definite by the guidance of consciousness, 
we must conceive it as standing apart from and exercising an 
overruling influence over that which it guides. This is un- 
questionably an essential characteristic of consciousness, as 
generally understood by those who take the trouble to con- 
sider its relation to behaviour ; and though some would seek 
to persuade us that a mere accompaniment of consciousness 
can somehow determine the continuance or discontinuance of 
organic behaviour, it is difficult to see how this can be the 
case. The accompaniment of air-tremors can no more influence 
the vibrations of a sounding string than an accompaniment of 
consciousness can affect the nature of the organic changes in 
the tentacles of the Sun-dew leaf. 
And if, instead of trusting to such general a priori con- 
siderations, we study with attention the conditions under which 
an animal so behaves as to lead us to infer that it profits 
by experience, we find that it is not the consciousness that 
