THE INDIVIDUAL AND THE SPECIES 205 



our intuitive knowledge of the actions of our own 

 bodies enables us to read into the characteristic atti- 

 tude represented in the marble all the other attitudes 

 of the series of movements, so our experience enables 

 us to expand the formal moment of becoming into the 

 action which it symbolises. 



This action has a purpose, an intention or design 

 which was contemplated before it began. There is 

 therefore the threefold meaning in the Platonic Idea : 

 (i) an immutable and essential Form of which we per- 

 ceive only the quality ; (2) the characteristic phase in 

 the transmutation of this Form into some other one ; and 

 (3) the design or intention of the transmutation. 



This was, as Bergson says, the natural metaphysics 

 of the intellect. It was, in reality, the " practical " 

 way of introducing order and simplification into the 

 confusion of the sensible world — all that is presented 

 to us by our intuitions. And in the effort to reduce 

 to order the welter of the organic world biology has 

 followed the same method, so that it represents the 

 species with the threefold significance of the Platonic 

 Idea. That which is expressed in the term species 

 is an assemblage of organisms each of which is defined 

 by an essential form and an essential mode of behaviour 

 — the characters indicated in the specific diagnosis. 

 But organisms are variable, their specific characters 

 fluctuate round a mean, and in saying this we sug- 

 gest that there is something which varies — there ought 

 to be an essential form from which the observed 

 forms of the individuals deviate, something invariable 

 which nevertheless varies accidentally. This is (i) the 

 quality of the specific idea. So also we never do 

 actually observe the essential individual ; what we 

 do see is the embryo, or the young and sexually im- 

 mature organism, or the sexually mature one, or the 



