What if a user finds that the computer is correctly configured whether he chooses to run programme A or programme B? Think carefully: there are only two possible explanations for this: either the computer "knows" in advance which programme the user is going to choose, or the computer can change the past. Impossible? Well something akin to this has been observed by physicists in the sub- atomic world of quantum mechanics, and at the very least, it is a point of departure for a discussion on the way in which we choose to live.

Physicists aside, people generally assume that the past is immutable; that it is their fate to live out some programme preordained by the master computer maker in our individual configurations. The present, we say, is contingent on the past, and the future on the present. Doctors tell us that our health is largely dependent on our genetic make-up, and that we are thus "predisposed" to diseases like diabetes and high blood pressure. Statistics show that if our parents lived to a ripe old age, then so too are we likely to be blessed with a long life. On the other hand, if one or other of our parents died from a heart attack or a stroke, we live in fear of a similar fate. Small fortunes are spent in laboratories and x-ray departments by people in search of a "diagnosis" - or a "clean bill of health" - as an indication of their particular configurations.

And the doctors are only too happy to go along, having been largely responsible for this mind set on the part of their patients in the first place. For a hundred and fifty years they have been classifying intense personal experiences into diagnostic categories with corresponding treatment protocols. If you have pains in your chest which are worse on exertion, spreading up to your jaw and down into your left arm then you have "angina" and you must put this little tablet below your tongue when you get the pain.

If your configuration is really bad, your "electrocardiogram" will indicate that you have "ischaemic heart disease"; your "coronary arteriograph" will show that the arteries carrying blood to your heart are eighty percent blocked, and if you do not have by-pass surgery, there is a greater than fifty percent chance that you will die from a heart attack within the next five years. If you cannot afford the by-pass surgery then your minimum obligation is to exercise when the doctors tell you to exercise and to eat what they tell you to eat.

And so it is that your life is laid out before you by cardiologists and their machines; cardiologists who are themselves suffering from coronary artery disease, and machines that have been configured with a limited number of outputs. Their diagnoses establish your options. They decide what your choices are, and if you are lucky enough to pass their "tests" you are enjoined to return again next year - and the next, and the next, until they can find something wrong to diagnose and treat.

Not everyone lives and dies according to doctors' diagnosticating. Some people decide for themselves how they are going to live. Some people go in search of health instead of disease. They focus on being well, even when the doctor has said that they are "sick".

Neither are such people deceived by that vacuous judgement: "I can't find anything wrong with you". They know when they have been abusing their health, and they understand that they cannot expect to continue doing so without paying a price. So instead of waiting to get sick, they make a commitment to change.

And how much can we change? Consider that some people diagnosed with cancer have gone on to complete remission and it would seem that the only limitations are those that we place on ourselves. Certainly a "diagnosis" is important for the doctor to do what he has to do. And when he has made his diagnosis, you should by all means follow the doctor's prescriptions; that is the best course to take in a medical frame of reference. But your own frame of reference must extend far beyond the medical. Indeed, there should be no fixed boundaries to your existence.

Live in a world of possibilities and anything is possible. Maybe the physicists are on to something. Could it be that past, present and future are merely percepts, each of which is contingent on the other two? Clairvoyants tell us that they do not predict the future but rather that they perceive what it will be in the context of the present. Change the present and the future will change. Maybe the same thing applies to the past. With enough faith in ourselves, we can be all that we want to be, and we may then find, in looking back over our lives, that that which we have chosen to become is what we have always been.