CONTINUITY OF BERGSON S THOUGHT 1 73 



whole story. In the case of slow variations, one accidental change at 

 a time would surely impair vision, and how could such a change be 

 retained by the principle of the best thing surviving ? It would not 

 wait for the complementary changes which are supposed to join and 

 complete it. 



In some ways, the sudden leap theory is better. If the eye of a 

 mollusc and that of a vertebrate have been evolved by relatively few 

 leaps, there is perhaps less difficulty in understanding the resemblance 

 of this organ in the two: chance, that is, seems less of a magician. 

 But when such sudden changes arise, why does not the animal become 

 blind ? How do all the parts of the delicate machinery of vision, 

 suddenly changed, remain co-ordinated so that the eye continues to 

 see? 



Of course the " law of correlation " will be invoked. But it doesn't 

 apply. We have not here to do with a collective whole of solidary 

 changes, but with a vast number of complementary changes most 

 delicately organized. That all these should occur in such a way as to 

 improve, or even to maintain, vision seems unthinkable under the 

 direction of such a principle as accident. Now what about Eimer's 

 orthogenesis ? Molluscs and vertebrates have certainly evolved 

 separately under the influence of light. Can we say that light has 

 caused the development ? 



We can imagine that light might act upon an organism in such a 

 way as to effect a gradual complication better adapted to the mold 

 of outward circumstances, but how could it affect the increasingly 

 complex structure of the eye itself ? In the one case, matter receives 

 a gradual imprint from light, in the other it becomes active and solves 

 a problem (of seeing better). At first, no doubt, the pigment-spot 

 may have been produced physically by the action of light, but when 

 the eye makes use of light to control locomotion, the "imprint" explana- 

 tion fails, because the eye is not now passive but active. The lower 

 down the phylogenetic scale we go, the more matter and the less life: 

 but higher up more life and less matter: the organism is now active, 

 not passive. Is this surprising ? It is like an orator who begins by 

 falling in with the mood of his audience, but on waking up to his work 



