G44 mAGMENTS OF SCIENCE. 



pared for its introduction, then, I think, he is right, and 

 that, as a matter of social policy, Dr. Haeckel would be 

 wrong in seeking to antedate the period of its introduction. 

 In dealing with the community great changes must have 

 timeliness as well as truth upon their side. But if the 

 mouths of thinkers be stopped, the necessary social prepa- 

 ration will be impossible; an unwholesome divorce will be 

 established between the expert and the public, 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 burden, however, of this celebrated lecture is a 

 warning that a marked distinction ought to be made be- 

 tween that which is experimentally proved, 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. 

 "Ik ought," as he poetically expresses it, " to be written 

 in small letters under the text." The audience ought to be 

 warned that speculative matter is only possible, not actual 

 truth that it belongs to the region of "belief," and not 

 to that of demonstration. As long as a problem continues 

 in this speculative stage it would be mischievous, he con- 

 siders, 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 

 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 T say is that 

 we have at present no right to set up this possible connec- 

 tion 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 

 says, " a strict distinction between what we wish to teach, 

 and what we wish to search for. The objects of our re- 

 search are expressed as problems (or hypotheses). We 



