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Lesson 37 |
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The process of ageing |
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What is one of the most unpleasant discoveries we make about ourselves as we get older? |
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At the age of twelve years, the human body is at its most vigorous. |
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It has yet to reach its full size and strength, |
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and its owner his or her full intelligence: but at this age the likelihood of death is least. |
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Earlier, we were infants and young children, and consequently more vulnerable; |
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later, we shall undergo a progressive loss of our vigour and resistance which, though imperceptible at first |
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will finally become so steep that we can live no longer, |
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however well we look after ourselves, and however well society, and our doctors, look after us. |
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This decline in vigour with the passing of time is called ageing. |
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It is one of the most unpleasant discoveries which we all make |
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that we must decline in this way, that if we escape wars, accidents and diseases we shall eventually 'die of old age', |
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and that this happens at a rate which differs little from person to person, |
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so that there are heavy odds in favour of our dying between the ages of 65 and 80. |
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Some of us will die sooner, a few will live longer--on into a ninth or tenth decade. |
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But the chances are against it, |
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and there is a virtual limit on how long we can hope to remain alive, however lucky and robust we are. |
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Normal people tend to forget this process unless and until they are reminded of it. |
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We are so familiar with the fact that man ages, |
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that people have for years assumed that the process of losing vigour with time, |
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of becoming more likely to die the older we get, was something self-evident |
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like the cooling of a hot kettle or the wearing-out of a pair of shoes. |
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They have also assumed that all animals, |
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and probably other organisms such as trees, or even the universe itself, must in the nature of things 'wear out'. |
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Most animals we commonly observe do in fact age as we do, |
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if given the chance to live long enough; |
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and mechanical systems like a wound watch, or the sun, |
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do in fact run out of energy in accordance with the second law of thermodynamics |
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(whether the whole universe does so is a moot point at present). |
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But these are not analogous to what happens when man ages. |
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A run-down watch is still a watch and can be rewound. |
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An old watch, by contrast, becomes so worn and unreliable that it eventually is not worth mending. |
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But a watch could never repair itself--it does not consist of living parts, only of metal, which wears away by friction. |
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We could, at one time, repair ourselves--well enough, at least, to overcome all but the most instantly fatal illnesses and accidents. |
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Between twelve and eighty years we gradually lose this power; |
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an illness which at 12 would knock us over, at 80 can knock us out, and into our grave. |
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If we could stay as vigorous as we are at twelve, |
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it would take about 700 years for half of us to die, and another 700 for the survivors to be reduced by half again. |
