sed 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 unlocked the muscle? The sense of pain, it may
be replied. But how can a sense of pain, or any other state of
consciousness, 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 consciousness 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 consciousness enter as
links into the chain of antecedence and sequence, which gives rise to
bodily actions? Speaking for myself, it is certain that I have no
power of imagining such states interposed between the molecules of the
brain, and influencing the transference of motion among the molecules.
The thing "eludes all mental presentation." Hence an iron strength
seems to belong to the logic which claims for the brain an automatic
action uninfluenced by consciousness. But it is, I believe, admitted
by those who hold the automaton theory, that states of consciousness
are produced by the motion of the molecules of the brain; and this
production of consciousness by molecular motion is to me quite as
unpresentable to the mental vision as the production of molecular
motion by consciousness. If I reject one result I must reject both.
I, however, reject neither, and thus stand in the presence of two
Incomprehensibles, instead of one Incomprehensible.' Here I secede
from the automaton theory, though maintained by friends who have all
my esteem, and fall back upon the avowal which occurs with such
wearisome iteration throughout the foregoing pages; namely, my own
utter incapacity to grasp the problem.

This avowal is repeated with emphasis in the passage to which
Professor Virchow's translator draws attention. What, I there
ask, is the causal connection between the objective and