that the investigator is in this case at the same time himself the object of the investigation and by this learns the secret of the inward process, his explanation of which would otherwise, like that of every other phenomenon, be brought to a standstill by an inscrutable force. And conversely, if we stood in the same inward relation towards every natural phenomenon as towards our own organism, the explanation of every natural phenomenon, as well as of all the properties of every body, would likewise ultimately be reduced to a will manifesting itself in them. For the difference does not reside in the thing itself, but in our relation to the thing. Wherever explanation of the physical comes to an end, it is met by the metaphysical; and wherever this last is accessible to immediate knowledge, the result will be, as here, the will. That even those parts of the body whose movements do not proceed from the brain, do not follow upon motives, and are not voluntary, are nevertheless ruled and animated by the will, is also shown by their participation in all unusually violent movements of the will, _i.e._ emotions and passions. We see, for instance, the quickened pulse in joy or alarm, the blush in embarrassment, the cheek's pallor in terror or in suppressed anger, the tears of sorrow, the difficult breathing and increased activity of the intestines in terror, watering of the mouth at the sight of dainties, nausea occasioned by that of loathsome objects, strongly accelerated circulation of the blood and even altered quality of bile through wrath, and of saliva through violent rage: this last even to the degree, that an excessively irritated dog may communicate hydrophobia by its bite without being itself affected with rabies, or even then contracting the disease--and the same is also asserted of cats and of cocks. The organism is further deeply undermined by lasting grief, and may be mortally affected by fright as well as by sudden joy. On the other hand, all those inner processes and changes which only have to do with the intellect and do not concern the will, however great may be their importance, remain without influence upon the machinery of the organism, with the one exception, that mental activity, prolonged to excess, fatigues and gradually exhausts the brain and finally undermines the organism. This again confirms the fact that the intellect is of a secondary character, and merely the organic function of a single part, a product of life; not the innermost kernel of our being, not the thing in itself, not metaphysical, incorporeal, eternal, like the will: the will never tires, never grows old, never learns, never improves by practice, is in infancy what it is in old age, eternally one and the same, and its character in each individual is unchangeable. Being essential moreover, it is likewise immutable, and therefore exists in animals as it does in us; for it does not, like the intellect, depend upon the perfection of the organization, but