The World as Will and Idea, Vol. II — Arthur Schopenhauer, trans. Haldane & Kemp

activity in general. Now if this striving is to realise itself, thus to manifest itself as movement, this movement must as such have some direction ; but this direction must be determined by something, i.e., it requires a guide, and this is the nervous system.

For to the mere irritability, as it lies in the muscular fibres and in itself is pure will, all directions are alike; thus it determines itself in no direction, but behaves like a body which is equally drawn in all directions ; it remains at rest.

Since the activity of the nerves comes in as motive (in the case of reflex movements as a stimulus), the striving force, i.e.t the irritability, receives a definite direction, and now produces the movements.

Yet those external acts of will which require no motives, and thus also no working up of mere stimuli into ideas in the brain, from which motives arise, but which follow immediately upon stimuli, for the most part inward stimuli, are the reflex movements, starting only from the spinal cord, as, for example, spasms and cramp, in which the will acts without the brain taking part.

In an analogous manner the will carries on the organic life, also by nerve stimulus, which does not proceed from the brain. Thus the will appears in every muscle as irritability, and is consequently of itself in a position to contract them, yet only in general; in order that some definite contraction should take place at a given moment, there is required here, as everywhere, a cause, which in this case must be a stimulus.

This is everywhere given by the nerve which goes into the muscle. If this nerve is in connection with the brain, then the contraction is a conscious act of will, i.e., takes place in accordance with motives, which, in consequence of external impressions, have arisen as ideas in the brain.

If the nerve is not in connection with the brain, but with the sympathicus maximus, then the contraction is involuntary and unconscious, an act connected with the maintenance of the organic life, and the nerve stimulus which causes it is occasioned by inward impressions ; for example, by the pressure upon the stomach of the food

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received, or of the chyme upon the intestines, or of the in-flowing blood upon the walls of the heart, in accordance with which the act is digestion, or motus peristalticus, or beating of the heart, &c.

But if now, in this process, we go one step further, we find that the muscles are the product of the blood, the result of its work of condensation, nay, to a certain extent they are merely solidified, or, as it were, clotted or crystallised blood ; for they have taken up into themselves, almost unaltered, its fibrin (cruor) and its colouring matter (Burdock's Physiologie, Bd. v. § 686).

But the force which forms the muscle out of the blood must not be assumed to be different from that which afterwards moves it as irritability, upon nerve stimulus, which the brain supplies ; in which case it then presents itself in self-consciousness as that which we call will.

The close connection between the blood and irritability is also shown by this, that where, on account of imperfection of the lesser circulation, part of the blood returns to the heart unoxidised, the irritability is also uncommonly weak, as in the batrachia.

Moreover, the movement of the blood, like that of the muscle, is independent and original ; it does not, like irritation, require the influence of the nerve, and is even independent of the heart, as is shown most clearly by the return of the blood through the veins to the heart ; for here it is not propelled by a vis a tergo, as in the case of the arterial circulation ; and all other mechanical explanations, such as a power of suction of the right ventricle of the heart, are quite inadequate. (See Burdock's Physiologie, Bd.

4, § 763, and Bosch, Ueber die Bedeutung des Blutes, §11, seq.) It is remarkable to see how the French, who recognise nothing but mechanical forces, controvert each other with insufficient grounds upon both sides ; and Bichat ascribes the flowing back of the blood through the veins to the pressure of the walls of the capillary tubes, and Magendie, on the other hand, to the continued action of the impulse of the heart (Pre'cis de Physiologie par Magendie, vol. ii. p.