VIRCHOW AND EVOLUTION. zyj 



able expansion of the powers which we now possess. We may think over the 

 subject again and again, but it eludes all intellectual presentation. Tlie 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, it is 

 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 no step toward its solution. And thus it will ever loom, compelling the 

 philosophies of successive ages to confess that — 



. . . . ' we are such stuff 

 As dreams are made of, and our little life 

 Is rounded by a sleep.' " 



In my work on " Heat," first published in 1863, I employ the precise 

 language here extracted from the Saturday Review. 



In this extract a distinction is revealed which I had resolved at all 

 hazards to draw — that, namely, between what men knew or might 

 know, and what they could never hope to know. Impart simple mag- 

 nifying power to our present vision, and the atomic motions of the 

 brain itself might be brought into view. Compare these motions with 

 the corresponding states of consciousness, and an empirical nexus might 

 be established ; but " we try to soar in a vacuum when we endeavor to 

 pass by logical deduction from the one to the other." Among those 

 brain-effects a new product appears which defies mechanical treatment. 

 We cannot deduce consciousness from motion, or motion from conscious- 

 ness, as we deduce one motion from another. Nevertheless observation 

 is open to us, and by it relations may be established which are at least 

 as valid as the conclusions of deductive reason. Tlie difficulty may 

 really lie in the attempt to convert a datum into an inference — an ulti- 

 mate fact into a product of logic. My desire for the moment, how- 

 ever, is, not to theorize, but to let fact speak in reply to accusation. 



The most " materialistic " speculation for which I am responsible, 

 prior to the " Belfast Address," is embodied in the following extract 

 from a brief article written as far back as 1865 : 



" Supposing the molecules of the human body, instead of replacing others, 

 and thus renewing a preexisting form, to be gathered first-hand from Nature, 

 and placed in the exact relative positions which they occupy in the body. 

 Supposing them to have the same forces and distribution of forces, the same 

 motions and distribution of motions — would this organized concourse of mole- 

 cules stand before us as a sentient, thinking being? There seems no valid rea- 

 son to assume that it would not. Or, supposing a planet carved from the sun set 

 spinning round an axis, and sent revolving round the sun at a distance equal 

 to that of our earth, would one consequence of the refrigeration of the mass be 

 the development of organic forms? I lean to the affirmative." 



This may be plain speaking, but it is without "dogmatism." An opin- 

 ion is expressed, a belief, a leaning — not an established " doctrine," 



