There is moreover special evidence that the movements induced by stimuli (involuntary movements) proceed from the will just as well as those occasioned by motives (voluntary movements): for instance, when the same movement follows now upon a stimulus, now again upon a motive, as is the case when the pupil of the eye is contracted. This movement, when caused by increased light, follows upon a stimulus; whereas, when occasioned by the wish to examine a very small object minutely in close proximity, it follows upon a motive; because contracting the pupil enables us to see things distinctly 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[203] relates 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. Müller[204] also tries to prove that the will acts upon the pupil. [203] E. H. Weber, "Additamenta ad E. H. Weberi tractatum de motu iridis." Lipsia, 1823. [204] Joh. Müller, "Handbuch der Physiologie," p. 764. The truth that the innermost mainspring of unconsciously 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 the special perception of the brain in which it presents itself together with the whole organism. Now by following the path of experimental research and hypotheses physiologists would never have arrived at the truth, that the last link in this ascending causal series is _the will_; it is known to them, on the contrary, in quite a different way. The solution of the enigma comes to them in a whisper from outside the investigation, owing to the fortunate circumstance