24 THE POPULAR SCIENCE MONTHLY. 



of that lime, to many, alas ! even now, evolution is materialism. But 

 materialism is atheism. Will some one say, the genuine Truth-seeker 

 follows where she seems to lead, whatever he the consequences? Yes ; 

 whatever be the consequences to one's self, to one's opinions, preju- 

 dices, theories, philosophies, but not to still more certain truth. Now, 

 to Agassiz, as to all genuine thinkers, the existence of God, like our 

 own existence, is more certain than any scientific theory, than anything 

 can possibly be made by proof. From his standpoint, therefore, he 

 was right in rejecting evolution as conflicting with still more certain 

 truth. The mistake which he made was in imagining that there was 

 any such conflict at all. But this was the universal mistake of the 

 age. A lesser man would have seen less clearly the higher truth and 

 accepted the lower. A greater man w^ould have risen above the age, 

 and seen that there was no conflict, and so accepted both. All think- 

 ing men are coming to this conclusion now, but none had done so then. 

 Now, then, at last, the obstacle of supernaturalism in the realm 

 of Nature having been removed by the establishment of the doctrine 

 of correlation of natural forces, and the extension of this doctrine to 

 embrace also life-force ; and now also a broad and firm basis of care- 

 fully-observed facts and well-established laws of succession of organic 

 forms having been laid by Agassiz, when again, for the third time, 

 the doctrine of origin of species " by derivation with modifications " 

 was brought forward by Darwin in a far more perfect form, with more 

 abundant illustrative materials, and with a new and most potent fac- 

 tor of modification — viz., divergent variations and natural selection — 

 it found the scientific world already fully prepared, and anxiously wait- 

 ing. I say anxiously waiting — for the supposed supernatural origin 

 of species had been the one exception to the otherwise universal law 

 of cause and effect, or the law of continuity. It was therefore an open 

 contradiction to the whole drift of scientific thought for five hundred 

 years. Is it any wonder, then, that the derivative origin of species 

 was welcomed with joy by the scientific world ? For five hundred 

 years, scientific thought, like a rising tide which knows no ebb, had 

 tended thitherward with ever-increasing pressure, but kept back by 

 the one supposed fact of the supernatural origin of species. Darwin 

 lifted the gate, and the in-rushing tide flooded the whole domain of 

 thought. 



What, then, is the place of Agassiz in biological science ? What 

 is the relation of Agassiz to Darwin — of Agassizian development to 

 Darwinian evolution ? I answer, it is the relation of formal science 

 to physical or causal science. Agassiz advanced biology to the formal 

 stage ; Darwin carried it forward, to some extent at least, to the phys- 

 ical stage. All true inductive sciences in their complete development 

 pass through these two stages. Science in the one stage treats of the 

 laics of phenomena ; in the other, of the causes or explanation of 

 these laws. The former must precede the latter, and form its founda- 



