PREFATORY NOTE. 



which all the world can understand. Sheridan is said 

 to have replied to some one who remarked on the 



easy flow of his style, " Easy reading, sir, is 



hard writing ; " and any one who is above the level of 

 a scientific charlatan will know that easy speaking is 

 " hard thinking." 



Again, when Professor Yirchow enlarges on the 

 extreme incompleteness of every man's knowledge 

 beyond those provinces which he has made his own 

 (and he might well have added within these also), 

 and when he dilates on the inexpediency, in the 

 interests of science, of putting forth as ascertained 

 truths propositions which the progress of knowledge 

 soon upsets who will be disposed to gainsay him ? 

 Xor have I, for one, anything but cordial assent to 

 give to his declaration, that the modern development 

 of science is essentially due to the constant encroach- 

 ment of experiment and observation on the domain of 

 hypothetical dogma; and that the most difficult, as 

 well as the most important, object of every honest 

 worker is " sick ent-siibjectiviren" to get rid of his 

 preconceived notions, and to keep his hypotheses 

 well in hand, as the good servants and bad masters 

 that they are. 



I do not think I have omitted any one of Professor 

 Virchow's main theses in this brief enumeration. I 

 do not find that they are disputed by Haeckel, and 



