When we talk about health in society today, we consider its death-rate or the life-span of its members. When we talk about the provision of health we talk about it as a social service—something which can be added to a community if there are sufficient facilities, hospitals, drugs, scalpels and men to wield them. At one moment we think of ourselves as healthy, able to work, to meet our commitments and carry out our responsibilities, to escape work and enjoy our leisure; at the next moment we are sick. Like a dirty pound note, we are taken out of circulation. We are sent to bed or to hospital, for between health and disease there is nothing.

This dichotomy is founded on a failure to understand health as the resultant of man’s inter-relationship with his physical and social environments. The static conception of health as a quality pertaining to one person at a given moment is due not only to early philosophical confusion about the nature of health, but to the mode of the scientific revolution in medicine in the last century. We shall have briefly to survey these before attempting a redefinition of health.

Western ideas on the nature of health can be traced to Galen. Living in a world whose prevailing philosophy was Stoicism, he considered perfect health to be the condition of perfect equilibrium and harmony; all that fell short comprised disease. In an excess of pessimism, however, he stated that if such a perfect condition existed, its existence would be momentary; and he covered his doubts, finally, by defining health as ‘that condition in which we do not suffer pain and are not impeded in the activities of life’. This was also expressed as: ‘All life consists of some measure of health which diminishes as death approaches.’

The element of determinism in his philosophy was to make his ideas especially popular with Christians later. In both theoretical systems there was room for ‘Vitalism’, the belief that there was some characteristic of the behaviour of the mind and body which would forever defy scientific investigation, and for the notion of entelechy, the internal purposiveness of the living organism.

A mechanistic philosophy was imposed on these earlier ideas by the discoveries made in the 17th century. Harvey, Descartes, and Borelli considered that the body, like a machine, has parts, each one susceptible to failure. Their mechanism must be studied and understood. As early as 1680 Borelli, a pioneer in studies of gravitation, wrote a treatise, De Motu Animalium, on the means of locomotion in terms of mechanics. Descartes envisaged living bodies as entirely subject to the laws of physics, in the sense that their actions could be interpreted according to these laws. The soul of the human organism had its own compartment, but in other respects the living organism could be considered as an automaton, whose treatment required the repair of damaged parts and the restitution of the different functions. This philosophy was reinforced in the 19th century when two tools reached a sufficient stage of development to bring about the scientific revolution of medicine. One was a technique—microscopy—which had developed from advances in the practice and theory of lens-making, the precision of the instrument-maker, and the science of fixing and staining dead tissues so as to change them as slightly as possible from the living. The other was a dimension in the scientific imagination. Without the imagery of machines, scientists lacked a language in which to formulate their ideas about the mechanisms of the body. Once thoroughly acquainted with machines, mills, pumps and engines, the scientist gained a model with which to describe the body. It was the use of such mechanical examples and language which, entangled ever since in our conception of the nature of disease, has limited the imagination by instrumental definitions of a process whose causes were far more extensive.