PROFESSOR VIRCHOW AND EVOLUTION. 397 



and the slow and natural process of leavening the social 

 lump by discovery and discussion will be displaced by 

 something far less safe and salutary. 



The burthen, however, of this celebrated lecture is a 

 warning that a marked distinction ought to be made be- 

 tween that which is experimentally pro ved,and that which 

 is still in the region of speculation. As to the latter, 

 Virchow by no means imposes silence. He is far too 

 sagacious a man to commit himself, at the present time 

 of day, to any such absurdity. But he insists that it 

 ought not to be put on the same evidential level as the 

 former. ' It ought,' as he poetically expresses it, ' to 

 be written in small letters under the text.' The 

 audience ought to be warned that the speculative 

 matter is only possible, not actual truth that it 

 belongs to the region of c belief,' and not to that, of 

 demonstration. As long as a problem continues in this 

 speculative stage it would be mischievous, he considers, 

 to teach it in our schools. ' We ought not,' he urges, 

 'to represent our conjecture as a certainty, nor our 

 hypothesis as a doctrine : this is inadmissible.' With 

 regard to the connection between physical processes and 

 mental phenomena he- says : ' I will, indeed, willingly 

 grant that we can find certain gradations, certain 

 definite points at which we trace a passage from mental 

 processes to processes purely physical, or of a physical 

 character. Throughout this discourse I am not asserting 

 that it will never be possible to bring psychical processes 

 into an immediate connection with those that are 

 physical. All I say is that we have at present no right 

 to set up this possible connection as a doctrine of 

 science.' In the next paragraph he reiterates his 

 position with reference to the introduction of such 

 topics into school teaching. We must draw,' he s ,ys, 

 a strict distinction between what we wish to teach, 



