1.1 THE VITAL IMPETUS 95 



other words, neither mechanism nor finalism will here be in 

 place, and we must resort to an explanation of a different 

 kind. Now, in the hypothesis we propose, the relation 

 of vision to the visual apparatus would be very nearly 

 that of the hand to the iron filings that follow, canalize 

 and limit its motion. 



The greater the effort of the hand, the farther it will 

 go into the filings. But at whatever point it stops, in- 

 stantaneously and automatically the filings coordinate 

 and find their equilibrium. So with vision and its organ. 

 According as the undivided act constituting vision ad- 

 vances more or less, the materiality of the organ is made 

 of a more or less considerable number of mutually co- 

 ordinated elements, but the order is necessarily complete 

 and perfect. It could not be partial, because, once again, 

 the real process which gives rise to it has no parts. That 

 is what neither mechanism nor finalism takes into account, 

 and it is what we also fail to consider when we wonder 

 at the marvelous structure of an instrument such as the 

 eye. At the bottom of our wondering is always this idea, 

 that it would have been possible for a part only of this 

 coordination to have been realized, that the complete 

 realization is a kind of special favor. This favor the 

 finalists consider as dispensed to them all at once, by the 

 final cause; the mechanists claim to obtain it little by 

 little, by the effect of natural selection; but both see 

 something positive in this coordination, and consequently 

 something fractionable in its cause, — something which 

 admits of every possible degree of achievement. In 

 reality, the cause, though more or less intense, cannot 

 produce its effect except in one piece, and completely 

 finished. According as it goes further and further in 

 the direction of vision, it gives the simple pigmentary 

 masses of a lower organism, or the rudimentary eye of 



