Machines that measure blood pressure (sphygmomanometers), like all other machines, sooner or later wear out.

I tend to hang on to my old instruments even when they are inconvenient to use, so long as they are still accurate. This is partly through affection for the familiar and partly through laziness. When a sphygmomanometer begins to wear out it leaks air when you pump it up and you have to keep pumping while you are taking a reading. My sphygmomanometer-before-last did this rather a lot towards the end of its life.

I remember an occasion when it was being particularly troublesome as I checked an old lady’s blood pressure. Listening to the air hissing out of the cuff as I pumped the cuff up around her wrinkled arm I gently broke the news: ‘Oh dear, oh dear — this poor old thing's nearly had it’.

Same sentence, but two contexts and therefore two meanings.

Fortunately the old lady saw the joke.

A lot of humour is based on double meaning, or punning. It seems to be the abrupt switch between two contexts which the same remark fits that does the trick. The better the remark fits both contexts, the more ludicrous the contrast between them, the more subtle the trigger that changes the understanding and causes the switch, the better the joke.

What does ‘ROM’ mean?

Easy! It means Right Otitis Media when I’m being a doctor and it means Read Only Memory when I’m being a computer buff.

OK. A more difficult one. What does ‘PID’ mean?

No problem. It means Prolapsed Intervertebral Disk when I’m dealing with a patient with back pain and Pelvic Inflammatory Disease when I’m dealing with a lady with certain other symptoms.

Consider the sentence, ‘With a bit of luck he’ll pull through’. This is the sort of light-hearted remark that I make when someone thinks their precious child is about to die of athletes foot. But what if one day I get it wrong and find myself listening to the same sentence being solemnly intoned by a coroner? Or by a prosecuting counsel? Or read it in the Sunday newspapers? What would it sound like then? In fact this is a risk I happily live with, like the risk of driving my car, but the point is the same; everything we say is ambiguous outside of its intended context. Everything in life is relative.

Words are far more ambiguous than we normally realise. I originally decided to illustrate this point by saying that the word ‘duck’ has a clear meaning but that we all recognise the ambiguity of a word like ‘kind’. Then I looked up both words in my dictionary and found that it gives sixteen meanings for the word ‘duck’ and only fourteen for ‘kind’!

When I scribble an address on a request form for a blood test it has to be transcribed onto a computer by a patient lady. (Not a lady patient you will immediately understand!) Now this lady works at the laboratory fifteen miles away and she doesn’t know the street names in our town, and she makes lots of mistakes.

But if I write the same address in the same (or even worse) handwriting for our community nursing colleagues, they have no difficulty going to the right house. How come?

Again, easy! The community nurses know the possibilities, they know the context and this vastly narrows down the possible interpretations of my scrawl (which was once described unkindly as the meanderings of a demented frog).

It is an interesting characteristic of intimate, human communication that we give the minimal clues to our meaning that we know a particular listener requires in order to understand us. This enables us to simultaneously exchange subliminal messages of sympathy. In this way exclusive ‘in-groups’ of all kinds, from elite corps of soldiers to subcultures like those formed by drug addicts, signal their brotherhood or sisterhood with a deliberately exclusive vocabulary.

By using obviously unnecessary clarity you can give an equally subtle but equally unmistakable message of exclusion. For example, ‘GOOD… MORN… INGE. HOW… ARE… YOOOU.?’, would be offensive unless spoken to someone who was very deaf, or very dim, or to a foreigner who spoke very poor English.

At a family breakfast, thanks to a confidently shared context of ideas, any one of a huge variety of inarticulate grunts might be correctly interpreted as ‘pass the toast’. And an elderly married couple who have shared a lifetime together can communicate the most intense emotions with hardly a word.

In each case the form of the communication is matched, with astonishing precision, to its intended audience — and this requires detailed knowledge of the likely context of ideas of that audience.

Similar considerations apply when we communicate with ourselves, for we certainly use words and other techniques to clarify, record and remember our own ideas. So, when you whistle a tune you know well you can hear it in your mind complete with full orchestra, massed choir and the feeling of a huge hall filled with an excited audience. Your conception of the fragment of tune you are whistling may include the effects of the preceding build-up and the climax that would follow in a full performance. Although they are just a few poor notes in the wind to an objective observer, in your own mind you can hear — and feel — a symphony.

It is the particular memory patterns which are evoked by the tune that transform it. The notes are meaningless without the context of memories waiting to be drawn into prominence by the action of whistling. For a passer-by who doesn’t share the context, the meaning which is so rich for you is completely missing.

So it doesn’t matter how beautifully you whistle, how much you wave your arms about, tap your feet and adopt an expression of rapturous abandonment. If a listener doesn’t share the environment of ideas in his mind which makes the tune meaningful he won’t understand. You may passionately want to transfer the whole complex of sound and feeling in your head so that you can share your love of it. But if your listener’s mind lacks the appropriate ideas you might as well be describing St Paul’s cathedral to a monkey in the jungle.

Even in your own mind, it may only be when you are in a particular mood that the seed of the tune can take root and flower. Sometimes it will mean nothing to you as well; on another occasion it may move you to tears.

The point here is that to communicate effectively, or indeed at all, we must be aware of the knowledge base of the person to whom we wish to communicate. This mutual understanding of the shared context of ideas is of the utmost importance to human relationships and communication, and to society in general. It is a matter of knowing the language, in the broadest sense of the term.

You may be wondering what qualifications I have for talking about these things and what relevance they have, anyway, to the theme of this book. The answer to the first question is not, for once, that I am a generalist and therefore interested in everything; it is that if we GPs are specialists in anything within the field of medicine, we are specialists in communication.

The answer to why this is relevant is that the shared context of ideas which is so essential for communication is the same, albeit hidden, background model of reality that we have been discussing.

A charming and courteous gentleman of the old school, a remarkable amateur naturalist whose encyclopaedic knowledge of plant names was slowly and tragically deserting him, stood with me in his hall ten minutes after he had found his wife dead in their shower. In his thread-bare tweed jacket he swayed a little against his stick as he contemplated the fact that he had drawn the longer of the two straws they had held together for so many years. Slightly the longer.

‘The sun has gone in. I always called her my sunshine.’

What can I say?

When words fail, we use analogy. An analogy has to be a word or phrase of which we know we already share an understanding with the listener. Thus we all understand the enormously rich complex of ideas and feelings evoked by the word ‘sunshine’ and understand deeply the significance of this description when applied by husband to his beloved wife. Putting the human force of this to one side if we can, without disrespect to its author, let’s try to analyse what is happening in this amazing process.

When the poet says ‘My love… is like a red, red rose’, he is taking two concepts that he knows the listener already has and inviting him to allow them to interact. The intention is that the listener will take whatever idea pattern may be evoked in his mind by the words ‘my love’ (presumably a girl the poet loves) and expose it to the pattern which is similarly evoked by the concept of a ‘red, red rose’. The automatic functions of the brain will then ensure that the two patterns seek out any aspects which, in the present context, fit together.

Countless ways in which the two patterns do not fit having been excluded, the mental image evoked by the phrase ‘my love’ is subtly distorted to incorporate appropriate aspects of the ‘rose’ pattern such as scent, beauty, summer, fresh air, femininity, etc. Describing the rose as ‘red, red…’ conveys further qualities of depth and richness and perhaps evokes blood and the heart. The listener places this new pattern on provisional status and awaits the continued context which may either reinforce these aspects, or alter them.

Sure enough, the poet continues by enhancing the image of his love by exposing it to further patterns of ideas: ‘melody… sweetly played… in tune…’

How could any listener fail to understand what makes the poet so enthusiastic about his love?

How much richer a means of communication this is than if he had said, ‘My girlfriend is incredibly wonderful!’.

But how infinitely richer than saying ‘My girlfriend is more wonderful than 99.97% of the female population aged between sixteen and thirty four in Chipping Norton and surrounding parishes.’!

But the last method is the one by which the increasingly reductionist, literal, mechanical, artificial world in which we live has to communicate its ideas.

Imagine one of the increasing number of self-confident new managers listening to this poem, learning about it, talking about it, until he gets the message. His eyes light up. He starts to smile. He says, ‘I see! He means that his love is like… like a very… an incredibly… ’.

He stops. The idea is there, but he can’t define it. Can’t pin it down. It is too large, too delicate, too subtle, to fit clearly into his consciousness all at once. He can’t begin to communicate his idea. The danger is that he will retreat into his simple, secure, materialistic world and pretend that he never really had the deeper experience. He will say, ‘I have it, I will construct a twenty four point rating scale for all aspects of feminine beauty and desirability and then show you how the poet’s love measures up’. Yes he will. Believe me, he will! I know because I’ve tried it myself.

Take this book. It is an idea. A large, subtle, delicate, complicated idea. Far too large to fit into my consciousness in one bite-sized, definable lump. You may manage better than me, but not much. People ask me what I am writing about and I can’t say — I mumble things about it being bigger than its parts. I say they wouldn’t understand unless they read it.

The point is that this size, this complexity, this subtlety is a strength not a weakness. The whole current ethos of our society, that things should be pinned down, defined, recorded and understood is, in this vitally important way, totally wrong.

If we think our machines are near to human understanding then we are like primitive tribesmen who think that their wooden images are near to being men. If we think that we can reproduce the functions of the human mind with a machine-like system of rules and regulations, however complex, we are deluding ourselves utterly. We need to look elsewhere for solutions to the inherent problems of progress.