PROFESSOR VIRCHOW AND EVOLUTION. 391 



tinuity between us and our loftier brothers yet to 

 come. 



' We have guarded ourselves against saying that 

 the inferring of thought from material combinations 

 and arrangements would be an inference a priori. The 

 inference meant would be the same in kind as that 

 which the observation of the effects of food and drink 

 upon the mind would enable us to make, differing only 

 from the latter in the degree of analytical insight which 

 we suppose attained. Given the masses and distances 

 of the planets, we can infer the perturbations consequent 

 on their mutual attractions. Given the nature of a 

 disturbance in water, air, or ether knowing the phys- 

 ical qualities of the medium we can infer how its parti- 

 cles will be affected. In all this we deal with physical 

 laws. The mind runs with certainty along the line of 

 thought which connects the phenomena, and from be- 

 ginning to end there is no break in the chain. But 

 when we endeavour to pass by a similar process from the 

 phenomena of physics to those of thought, we meet a 

 problem which transcends any conceivable expansion of 

 the powers which we now possess. We may think over 

 the subject again and again, but it eludes all intellectual 

 presentation. We stand at length face to face with the 

 Incomprehensible. The territory of physics is wide, 

 but it has its limits from which we look with vacant 

 gaze into the region beyond. Let us follow matter to its 

 utmost bounds, let us claim it in all its forms even in 

 the muscles, blood, and brain of man himself as ours 

 to experiment with and to speculate upon. Casting 

 the term "vital force" from our vocabulary, let us 

 reduce, if we can, the visible phenomena of life to 

 mechanical attractions and repulsions. Having thus 

 exhausted physics, and reached its very rim, a mighty 

 Mystery still looms beyond us. We have, in fact, made 



