An Essay on the Principle of Population

by T. R. Malthus

Mr Godwin's conjecture concerning the indefinite prolongation of human life—Improper inference drawn from the effects of mental stimulants on the human frame, illustrated in various instances—Conjectures not founded on any indications in the past not to be considered as philosophical conjectures—Mr Godwin's and Mr Condorcet's conjecture respecting the approach of man towards immortality on earth, a curious instance of the inconsistency of scepticism.

Mr Godwin's conjecture respecting the future approach of man towards immortality on earth seems to be rather oddly placed in a chapter which professes to remove the objection to his system of equality from the principle of population. Unless he supposes the passion between the sexes to decrease faster than the duration of life increases, the earth would be more encumbered than ever. But leaving this difficulty to Mr Godwin, let us examine a few of the appearances from which the probable immortality of man is inferred.

To prove the power of the mind over the body, Mr Godwin observes, "How often do we find a piece of good news dissipating a distemper? How common is the remark that those accidents which are to the indolent a source of disease are forgotten and extirpated in the busy and active? I walk twenty miles in an indolent and half determined temper and am extremely fatigued. I walk twenty miles full of ardour, and with a motive that engrosses my soul, and I come in as fresh and as alert as when I began my journey. Emotion excited by some unexpected word, by a letter that is delivered to us, occasions the most extraordinary revolutions in our frame, accelerates the circulation, causes the heart to palpitate, the tongue to refuse its office, and has been known to occasion death by extreme anguish or extreme joy. There is nothing indeed of which the physician is more aware than of the power of the mind in assisting or reading convalescence."

The instances here mentioned are chiefly instances of the effects of mental stimulants on the bodily frame. No person has ever for a moment doubted the near, though mysterious, connection of mind and body. But it is arguing totally without knowledge of the nature of stimulants to suppose, either that they can be applied continually with equal strength, or if they could be so applied, for a time, that they would not exhaust and wear out the subject. In some of the cases here noticed, the strength of the stimulus depends upon its novelty and unexpectedness. Such a stimulus cannot, from its nature, be repeated often with the same effect, as it would by repetition lose that property which gives it its strength.

In the other cases, the argument is from a small and partial effect, to a great and general effect, which will in numberless instances be found to be a very fallacious mode of reasoning. The busy and active man may in some degree counteract, or what is perhaps nearer the truth, may disregard those slight disorders of frame which fix the attention of a man who has nothing else to think of; but this does not tend to prove that activity of mind will enable a man to disregard a high fever, the smallpox, or the plague.

The man who walks twenty miles with a motive that engrosses his soul does not attend to his slight fatigue of body when he comes in; but double his motive, and set him to walk another twenty miles, quadruple it, and let him start a third time, and so on; and the length of his walk will ultimately depend upon muscle and not mind. Powell, for a motive of ten guineas, would have walked further probably than Mr Godwin, for a motive of half a million. A motive of uncommon power acting upon a frame of moderate strength would, perhaps, make the man kill himself by his exertions, but it would not make him walk a hundred miles in twenty-four hours. This statement of the case shews the fallacy of supposing that the person was really not at all tired in his first walk of twenty miles, because he did not appear to be so, or, perhaps, scarcely felt any fatigue himself. The mind cannot fix its attention strongly on more than one object at once. The twenty thousand pounds so engrossed his thoughts that he did not attend to any slight soreness of foot, or stiffness of limb. But had he been really as fresh and as alert, as when he first set off, he would be able to go the second twenty miles with as much ease as the first, and so on, the third, &c. Which leads to a palpable absurdity. When a horse of spirit is nearly half tired, by the stimulus of the spur, added to the proper management of the bit, he may be put so much upon his mettle, that he would appear to a standerby, as fresh and as high spirited as if he had not gone a mile. Nay, probably, the horse himself, while in the heat and passion occasioned by this stimulus, would not feel any fatigue; but it would be strangely contrary to all reason and experience, to argue from such an appearance that, if the stimulus were continued, the horse would never be tired. The cry of a pack of hounds will make some horses, after a journey of forty miles on the road, appear as fresh, and as lively, as when they first set out. Were they then to be hunted, no perceptible abatement would at first be felt by their riders in their strength and spirits, but towards the end of a hard day, the previous fatigue would have its full weight and effect, and make them tire sooner. When I have taken a long walk with my gun, and met with no success, I have frequently returned home feeling a considerable degree of uncomfortableness from fatigue. Another day, perhaps, going over nearly the same extent of ground with a good deal of sport, I have come home fresh, and alert. The difference in the sensation of fatigue upon coming in, on the different days, may have been very striking, but on the following mornings I have found no such difference. I have not perceived that I was less stiff in my limbs, or less footsore, on the morning after the day of the sport, than on the other morning.

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.

The probable increase of the voluntary power of man over his animal frame comes next under Mr Godwin's consideration, and he concludes by saying, that the voluntary power of some men, in this respect, is found to extend to various articles in which other men are impotent. But this is reasoning against an almost universal rule from a few exceptions; and these exceptions seem to be rather tricks, than powers that may be exerted to any good purpose. I have never heard of any man who could regulate his pulse in a fever, and doubt much, if any of the persons here alluded to have made the smallest perceptible progress in the regular correction of the disorders of their frames and the consequent prolongation of their lives.