130 EVOLUTION AND MAN S PLACE IN NATURE 



apparatus, and which cannot be scientifically explained 

 by functions belonging to terminal organs, nerve 

 fibres, and brain. 



Recognition of rational causality, involving indivi 

 dual responsibility for one s own thought, becomes a 

 turning-point in this discussion. The facts to be 

 explained in human life are now seen in their natural 

 proportions, invisible at any nearer point of our ap 

 proach. In order to give a scientific view of man s 

 place in Nature, we must account for this rational caus 

 ality, tracing the history of its origin on the earth. The 

 causality of organic life, and the causality of rational 

 life, are now seen in contrast. The outcome of the 

 one is mechanical movement, responding to sensory 

 impression ; the outcome of the other is thought, first 

 appearing in observation. For organic life, the 

 condition of improvement is nutriment ; for rational 

 life the condition is self-criticism. In the realm of 

 natural history there are thus two distinct orders of 

 life at work ; and these are combined in human life ; 

 they are not continuous : the sensory process is dis 

 continuous. These two cannot be compared, as if the 

 higher were only an advanced stage of animal life. 

 Rational life cannot be judged by muscular develop 

 ment, as judges decide in a cattle-show. All that 

 has been ascertained regarding rudiments of organs, 

 homologies in structure, and continuity of 

 organic life, retains its value as a contribution to 

 natural history; but it has no scientific worth for 

 explanation of rational causality. Whatever may 

 afterwards be said about the higher mammals, it is 

 impossible to maintain continuity of life from the 

 lower forms of organism up to the rational or reflec- 



