Wealth is not a simple concept, as King Midas discovered when his food turned to gold. Gold, or money, represents wealth as a means for exchange, but as we rediscover in times of crisis or war, money is not itself a useful resource. Nothing is more useful for life than life itself, and health through which to enjoy it. This is not the only sort of wealth which the NHS produces, but like all health care systems, whether for fees, profit or public service, this purports to be its principal product.

For commercial health care, for professional or corporate trade, health gain is in fact a byproduct. It is necessarily subordinated to the profit required to justify the business of either entrepreneur professionals or corporate providers. Only through public service is it possible to set health gain as a planned social goal and a direct objective. However, even if this possibility is pursued in practice, health gain is not the only product.

Health gain can be measured as the aggregate of healthier births, healthier lives and healthier deaths. All public care systems have other social products, the most important of which is stabilisation of society by legitimising the state (or the power of other corporate providers), but any system depends on this central promise of health gain for its credibility, whether this promise is real or illusory.

Healthier births are easily measured by maternal, perinatal and infant mortality rates, but in fully industrialised economies these are generally too low to provide more than a crude measure of output. Measuring healthier lives is difficult. To include all the possible impairments of life which health care tries to address, useful measures of healthier lives can only be essentially subjective measures of happiness and contentment, supplemented by measures of function – what people can or cannot do, not only individually, but as families, communities, nations and (as we are at last being compelled by events to recognise) as our entire human species, trying to survive on this planet. Measuring scales exist for all of these, but are not much used, because we still underestimate the value of subjective measurements, and overestimate the value of objective measurements such as X-rays, blood tests and so on.