In all these cases, stimulants upon the mind seem to act rather by taking off the attention from the bodily fatigue, than by really and truly counteracting it.  If the energy of my mind had really counteracted the fatigue of my body, why should I feel tired the next morning? if the stimulus of the hounds had as completely overcome the fatigue of the journey in reality, as it did in appearance, why should the horse be tired sooner than if he had not gone the forty miles?  I happen to have a very bad fit of the toothache at the time I am writing this.  In the eagerness of composition, I every now and then, for a moment or two, forget it.  Yet I cannot help thinking that the process, which causes the pain, is still going forwards, and that the nerves which carry the information of it to the brain are even during these moments demanding attention and room for their appropriate vibrations.  The multiplicity of vibrations of another kind may perhaps prevent their admission, or overcome them for a time when admitted, till a shoot of extraordinary energy puts all other vibration to the rout, destroys the vividness of my argumentative conceptions, and rides triumphant in the brain.  In this case, as in the others, the mind seems to have little or no power in counteracting or curing the disorder, but merely possesses a power, if strongly excited, of fixing its attention on other subjects.

I do not, however, mean to say that a sound and vigorous mind has no tendency whatever to keep the body in a similar state.  So close and intimate is the union of mind and body that it would be highly extraordinary if they did not mutually assist each other’s functions.  But, perhaps, upon a comparison, the body has more effect upon the mind than the mind upon the body.  The first object of the mind is to act as purveyor to the wants of the body.  When these wants are completely satisfied, an active mind is indeed apt to wander further, to range over the fields of science, or sport in the regions of.  Imagination, to fancy that it has ‘shuffled off this mortal coil’, and is seeking its kindred element.  But all these efforts are like the vain exertions of the hare in the fable.  The slowly moving tortoise, the body, never fails to overtake the mind, however widely and extensively it may have ranged, and the brightest and most energetic intellects, unwillingly as they may attend to the first or second summons, must ultimately yield the empire of the brain to the calls of hunger, or sink with the exhausted body in sleep.

It seems as if one might say with certainty that if a medicine could be found to immortalize the body there would be no fear of its [not] being accompanied by the immortality of the mind.  But the immortality of the mind by no means seems to infer the immortality of the body.  On the contrary, the greatest conceivable energy of mind would probably exhaust and destroy the strength of the body.  A temperate vigour of mind appears to be favourable to health, but very great intellectual exertions tend rather, as has been often observed, to wear out the scabbard.  Most of the instances which Mr Godwin has brought to prove the power of the mind over the body, and the consequent probability of the immortality of man, are of this latter description, and could such stimulants be continually applied, instead of tending to immortalize, they would tend very rapidly to destroy the human frame.