54 CREATIVE EVOLUTION [chap. 



our hypothesis is justified, if the essential causes working 

 along these diverse roads are of psychological nature, they 

 must keep something in common in spite of the divergence 

 of their effects, as school-fellows long separated keep the 

 same memories of boyhood. Roads may fork or by-ways 

 be opened along which dissociated elements may evolve 

 in an independent manner, but nevertheless it is in virtue 

 of the primitive impetus of the whole that the movement of 

 the parts continues. Something of the whole, therefore, 

 must abide in the parts; and this common element will 

 be evident to us in some way, perhaps by the presence of 

 identical organs in very different organisms. Suppose, 

 for an instant, that the mechanistic explanation is the true 

 one: evolution must then have occurred through a series 

 of accidents added to one another, each new accident 

 being preserved by selection if it is advantageous to that 

 sum of former advantageous accidents which the present 

 form of the living being represents. What likelihood is 

 there that, by two entirely different series of accidents 

 being added together, two entirely different evolutions 

 will arrive at similar results? The more two lines of evo- 

 lution diverge, the less probability is there that accidental 

 outer influences or accidental inner variations bring about 

 the construction of the same apparatus upon them, es- 

 pecially if there was no trace of this apparatus at the 

 moment of divergence. But such similarity of the two 

 products would be natural, on the contrary, on a hypothesis 

 like ours : even in the latest channel there would be some- 

 thing of the impulsion received at the source. Pure 

 mechanism, then, would be refutable, and finality, in the 

 special sense in which we understand it, would be demon- 

 strable in a certain aspect, if it could be proved that life may 

 manufacture the like apparatus, by unlike means, on di- 

 vergent lines of evolution; and the strength of the proof 



