THE WORLD OF LIVING ORGANISMS 139 



mark-organs of an animal, and could determine the indications 

 belonging to it, yet all we could say for certain would be, — 

 " This animal fixes the limits between the qualities in the way 

 we do, or in a different way from what we do." But as to 

 the qualities themselves, we could state nothing further. An 

 outside observer can never do so, for that would require his 

 being able to get inside the mind of the animal itself. 



Now in the great majority of cases we are in complete 

 ignorance concerning the mark-organs of animals, and are 

 compelled to deduce these from the indications to which the 

 animals react. The indications that we study in this way 

 are equipped with our human qualities, and there is nothing 

 for us to do but to use them just as they are. But we shall 

 fall into the crudest sort of error if we have not learnt to 

 analyse the objects that we observe in their effect on animals 

 so thoroughly that we are in a position to treat the qualities 

 as independent factors. For it follows from what we have 

 been saying, that every impression of every object is analysed 

 down to its finest detail at the periphery of the animal, by 

 being taken up into countless nerve-persons ; and it is only 

 afterwards, in the mark-organ, that synthesis occurs. And 

 for this synthesis there are various rules, which we can test 

 only by comparing them with the rules known to us from 

 the way in which our own implements are composed. 



Now suddenly we see why it is that we cannot omit from 

 biology the study of the theory qf knowledge. For this alone 

 teaches us to reduce our human indications to the simplest 

 factors, and then to combine them once more. 



All implements in the world are really nothing but human 

 indications. If we want to study those of animals, we must 

 know the fundamental factors of which the human ones are 

 composed, and by what rules this composition takes place. 



Anything else is sheer amateurishness. 



To ascertain correctly what are an animal's indications 



