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PHYSIOLOGY AND PATHOLOGY. 245
cause contracting the pupil enables us to see things dis
tinctly even when quite near to us, and this distinctness
may be increased by our looking through a hole pierced
in a card with a pin ; conversely, the pupil is dilated when
we look at distant objects. Surely the same movement of
the same organ is not likely to proceed alternately from
two fundamentally different sources. E. H. Weber 1
re
lates that he discovered in himself the power of dilating
and contracting at will the pupil of one of his eyes, while
looking at the same object, so as to make that object
appear now distinct, now indistinct, while the other eye
remained closed. Joh. Miiller 2 also tries to prove that the
will acts upon the pupil.
The truth that the innermost mainspring of uncon
sciously performed vital and vegetative functions is the
will, we find moreover confirmed by the consideration, that
even the movement of a limb recognised as voluntary, is
only the ultimate result of a multitude of preceding changes
which have taken place inside that limb and which no more
enter into our consciousness than those organic functions.
Yet these changes are evidently that which was first set
in motion by the will, the movement of the limb being merely
their remote consequence ; nevertheless this remains so
foreign to our consciousness that physiologists try to reach it
by means of such hypotheses as these : that the sinews and
muscular fibre are contracted by a change in the cellular
tissue wrought by a precipitation of the blood-vapour in
that tissue to serum ; but that this change is brought
about by the nerve s action, and this by the will. Thus,
even here, it is not the change which proceeded originally
from the will which comes into consciousness, but only its
remote result ; and even this, properly speaking, only through
1
E. H. Weber,
iridis." Lipsia, 1823.
2 Joh. Miiller,
"
Additamenta ad E. H. Weberi tractatum de motn
" Handbuch der Physiologic," p. 764.