PROFESSOR VIRCHO W AND E VOL UTION. 651 
are content to make your soul a poetic rendering of a 
phenomenon which refuses the yoke of ordinary physical 
laws, I, for one, would not object to this exercise of 
ideality/"** Professor Virchow's meaning, I admit, re- 
quired illustration; but I do not clearly see how the 
quotation from me subserves this purpose. I do not even 
know whether I am cited as meriting praise or deserving 
opprobrium. In a far coarser fashion this utterance of 
mine has been dealt with in other places: it may therefore 
be worth while to spend a few words upon it. 
The sting of a wasp at the finger-end announces itself to 
the brain as pain. The impression made by the sting 
travels, in the first place, with comparative slowness along 
the nerves affected; and only when it reaches the brain 
have we the fact of consciousness. Those who think most 
pofoundly on this subject hold that a chemical change, 
which, strictly interpreted, is atomic motion, is in such a 
case, propagated along the nerve, and communicated to 
the brain. Again, on feeling the sting* I flap the insect 
violently away. What has caused this motion of my hand? 
The command from the brain to remove the insect travels 
along the motor nerves to., the proper muscles, and, their 
force being unlocked, they perform the work demanded of 
them. But what moved the nerve molecules which un- 
locked the muscle? The sense of pain, it may be replied. 
But how can a sense of pain, or any other state of conscious- 
ness, make matter move? Not all the sense of pain or 
pleasure in the world could lift a stone or move a billiard- 
ball; why should it stir a molecule? Try to express the 
motion numerically in terms of the sensation, and the 
difficulty immediately appears. Hence the idea long ago 
entertained by philosophers, but lately brought into special 
prominence, that the physical processes are complete in 
themselves, and would go on just as they do if conscious- 
ness were not at all implicated. Consciousness, on this 
view, is a kind of by-product inexpressible in terms of 
force and motion, and unessential to the molecular changes 
going on in the brain. 
Four years ago, I wrote thus: "Do states of conscious- 
ness enter as links into the chain of antecedence and 
* Presidential address delivered before the Birmingham and Mid- 
land Institute, October 1, 1877. Fortnightly Review, Nov. 1, 
1877, p. 607. 
