6 CHARLES DARWIN 



way from era to era. This is tlie doctrine of the fixity 

 and immutability of species, almost universal in the 

 civilised world up to the end of the last century. 



Improbable as such a crude idea now seems to any 

 person even moderately acquainted with the extra- 

 ordinary variety and variability of living forms, it 

 nevertheless contained nothing at all likely to con- 

 tradict the ordinary experience of the everyday observer 

 in the last century. The handful of plants and animals 

 with which he was personally acquainted consisted for 

 the most part of a few large, highly advanced, and 

 well-marked forms, not in the least liable to be mistaken 

 for one another even by the most hasty and casual 

 spectator. A horse can immediately be discriminated 

 by the naked eye from a donkey, and a cow from a 

 sheep, without risk of error; nobody is likely to confuse 

 wheat with barley, or to hesitate between classing any 

 given fruit that is laid before him as a pear or an apple, 

 a plum or a nectarine. Variability seldom comes under 

 the notice of the ordinary passing spectator as it does 

 under that of the prying and curious scientific observer ; 

 and when it comes at all, as in the case of dogs and 

 pigeons, roses and hyacinths, it is no doubt set down 

 carelessly on a superficial 'view as a mere result of 

 human selection or of deliberate mongrel interbreed- 

 ing. To the eye of the average man, all the living 

 objects ordinarily perceived in external nature fall at 

 once under certain fixed and recognisable kinds, as 

 dogs and horses, elms and ashes, whose limits he is 

 never at all inclined to confound in any way one with 

 the other. 



Linnaeus, the great father of modern scientific 



