chapter 28
, confirms the primacy of the will in self-consciousness.
12. On the other hand, nothing proves more clearly the secondary, dependent, conditioned nature of the _intellect_ than its periodical intermittance. In deep sleep all knowing and forming of ideas ceases. But the kernel of our nature, the metaphysical part of it which the organic functions necessarily presuppose as their _primum mobile_, must never pause if life is not to cease, and, moreover, as something metaphysical and therefore incorporeal, it requires no rest. Therefore the philosophers who set up a _soul_ as this metaphysical kernel, _i.e._, an originally and essentially _knowing_ being, see themselves forced to the assertion that this soul is quite untiring in its perceiving and knowing, therefore continues these even in deep sleep; only that we have no recollection of this when we awake. The falseness of this assertion, however, was easy to see whenever one had rejected that _soul_ in consequence of Kant’s teaching. For sleep and waking prove to the unprejudiced mind in the clearest manner that knowing is a secondary function and conditioned by the organism, just like any other. Only the _heart_ is untiring, because its beating and the circulation of the blood are not directly conditioned by nerves, but are just the original manifestation of the will. Also all other physiological functions governed merely by ganglionic nerves, which have only a very indirect and distant connection with the brain, are carried on during sleep, although the secretions take place more slowly; the beating of the heart itself, on account of its dependence upon respiration, which is conditioned by the cerebral system (_medulla oblongata_), becomes with it a little slower. The stomach is perhaps most
## active in sleep, which is to be attributed to its special consensus with
the now resting brain, which occasions mutual disturbances. The _brain_ alone, and with it knowing, pauses entirely in deep sleep. For it is merely the minister of foreign affairs, as the ganglion system is the minister of the interior. The brain, with its function of knowing, is only a _vedette_ established by the will for its external ends, which, up in the watch-tower of the head, looks round through the windows of the senses and marks where mischief threatens and where advantages are to be looked for, and in accordance with whose report the will decides. This _vedette_, like every one engaged on active service, is then in a condition of strain and effort, and therefore it is glad when, after its watch is completed, it is again withdrawn, as every watch gladly retires from its post. This withdrawal is going to sleep, which is therefore so sweet and agreeable, and to which we are so glad to yield; on the other hand, being roused from sleep is unwelcome, because it recalls the _vedette_ suddenly to its post. One generally feels also after the beneficent systole the reappearance of the difficult diastole, the reseparation of the intellect from the will. A so-called _soul_, which was originally and radically a _knowing_ being, would, on the contrary, necessarily feel on awaking like a fish put back into water. In sleep, when merely the vegetative life is carried on, the will works only according to its original and essential nature, undisturbed from without, with no diminution of its power through the
## activity of the brain and the exertion of knowing, which is the heaviest
organic function, yet for the organism merely a means, not an end; therefore, in sleep the whole power of the will is directed to the maintenance and, where it is necessary, the improvement of the organism. Hence all healing, all favourable crises, take place in sleep; for the _vis naturæ medicatrix_ has free play only when it is delivered from the burden of the function of knowledge. The embryo which has still to form the body therefore sleeps continuously, and the new-born child the greater part of its time. In this sense Burdach (_Physiologie_, vol. iii. p. 484) quite rightly declares sleep to be the _original state_.
With reference to the brain itself, I account to myself for the necessity of sleep more fully through an hypothesis which appears to have been first set up in Neumann’s book, “_Von den Krankheiten des Menschen_,” 1834, vol. 4, § 216. It is this, that the nutrition of the brain, thus the renewal of its substance from the blood, cannot go on while we are awake, because the very eminent organic function of knowing and thinking would be disturbed or put an end to by the low and material function of nutrition. This explains the fact that sleep is not a purely negative condition, a mere pausing of the activity of the brain, but also shows a positive character. This makes itself known through the circumstance that between sleep and waking there is no mere difference of degree, but a fixed boundary, which, as soon as sleep intervenes, declares itself in dreams which are completely different from our immediately preceding thoughts. A further proof of this is that when we have dreams which frighten us we try in vain to cry out, or to ward off attacks, or to shake off sleep; so that it is as if the connecting-link between the brain and the motor nerves, or between the cerebrum and the cerebellum (as the regulator of movements) were abolished; for the brain remains in its isolation and sleep holds us fast as with brazen claws. Finally, the positive character of sleep can be seen in the fact that a certain degree of strength is required for sleeping. Therefore too great fatigue or natural weakness prevent us from seizing it, _capere somnum_. This may be explained from the fact that the _process of nutrition_ must be introduced if sleep is to ensue: the brain must, as it were, begin to feed. Moreover, the increased flow of blood into the brain during sleep is explicable from the nutritive process; and also the position of the arms laid together above the head, which is instinctively assumed because it furthers this process: also why children, so long as their brain is still growing, require a great deal of sleep, while in old age, on the other hand, when a certain atrophy of the brain, as of all the parts, takes place, sleep is short; and finally why excessive sleep produces a certain dulness of consciousness, the consequence of a certain hypertrophy of the brain, which in the case of habitual excess of sleep may become permanent and produce imbecility: ανιη και πολυς ὑπνος (_noxæ est etiam multus somnus_), Od. 15, 394. The need of sleep is therefore directly proportionate to the intensity of the brain-life, thus to the clearness of the consciousness. Those animals whose brain-life is weak and dull sleep little and lightly; for example, reptiles and fishes: and here I must remind the reader that the winter sleep is sleep almost only in name, for it is not an inaction of the brain alone, but of the whole organism, thus a kind of apparent death. Animals of considerable intelligence sleep deeply and long. Men also require more sleep the more developed, both as regards quantity and quality, and the more active their brain is. Montaigne relates of himself that he had always been a long sleeper, that he had passed a large part of his life in sleeping, and at an advanced age still slept from eight to nine hours at a time (Liv. iii., chap. 13). Descartes also is reported to have slept a great deal (Baillet, _Vie de Descartes_, 1693, p. 288). Kant allowed himself seven hours for sleep, but it was so hard for him to do with this that he ordered his servant to force him against his will, and without listening to his remonstrances, to get up at the set time (Jachmann, _Immanuel Kant_, p. 162). For the more completely awake a man is, _i.e._, the clearer and more lively his consciousness, the greater for him is the necessity of sleep, thus the deeper and longer he sleeps. Accordingly much thinking or hard brain-work increases the need of sleep. That sustained muscular exertion also makes us sleepy is to be explained from the fact that in this the brain continuously, by means of the _medulla oblongata_, the spinal marrow, and the motor nerves, imparts the stimulus to the muscles which affects their irritability, and in this way it exhausts its strength. The fatigue which we observe in the arms and legs has accordingly its real seat in the brain; just as the pain which these parts feel is really experienced in the brain; for it is connected with the motor nerves, as with the nerves of sense. The muscles which are not actuated from the brain—for example, those of the heart—accordingly never tire. The same grounds explain the fact that both during and after great muscular exertion we cannot think acutely. That one has far less energy of mind in summer than in winter is partly explicable from the fact that in summer one sleeps less; for the deeper one has slept, the more completely awake, the more lively, is one afterwards. This, however, must not mislead us into extending sleep unduly, for then it loses in intension, _i.e._, in deepness and soundness, what it gains in extension; whereby it becomes mere loss of time. This is what Goethe means when he says (in the second part of “Faust”) of morning slumber: “Sleep is husk: throw it off.” Thus in general the phenomenon of sleep most specially confirms the assertion that consciousness, apprehension, knowing, thinking, is nothing original in us, but a conditioned and secondary state. It is a luxury of nature, and indeed its highest, which it can therefore the less afford to pursue without interruption the higher the pitch to which it has been brought. It is the product, the efflorescence of the cerebral nerve-system, which is itself nourished like a parasite by the rest of the organism. This also agrees with what is shown in our third book, that knowing is so much the purer and more perfect the more it has freed and severed itself from the will, whereby the purely objective, the æsthetic comprehension appears. Just as an extract is so much the purer the more it has been separated from that out of which it is extracted and been cleared of all sediment. The opposite is shown by the _will_, whose most immediate manifestation is the whole organic life, and primarily the untiring heart.
This last consideration is related to the theme of the following chapter, to which it therefore makes the transition: yet the following observation belongs to it. In magnetic somnambulism the consciousness is doubled: two trains of knowledge, each connected in itself, but quite different from each other, arise; the waking consciousness knows nothing of the somnambulent. But the will retains in both the same character, and remains throughout identical; it expresses in both the same inclinations and aversions. For the function may be doubled, but not the true nature.
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