Lifestyle and Medicine in the Enlightenment

The Six Non-Naturals in the Long Eighteenth Century

James Kennaway, Rina Knoeff

• Publisher: Routledge
• Year: 2020
• ISBN:
  9780429879241
• Edition: 1
• Topic: History
• Subtopic: World History
• Index: History

The biggest challenges in public health today are often related to attitudes, diet and exercise. In many ways, this marks a return to the state of medicine in the eighteenth century, when ideals of healthy living were a much more central part of the European consciousness than they have become since the advent of modern clinical medicine. Enlightenment advice on healthy lifestyle was often still discussed in terms of the six non-naturals – airs and places, food and drink, exercise, excretion and retention, and sleep and emotions. This volume examines what it meant to live healthily in the Enlightenment in the context of those non-naturals, showing both the profound continuities from Antiquity and the impact of newer conceptions of the body.

Chapter 8 of this book is freely available as a downloadable Open Access PDF under a Creative Commons Attribution-Non Commercial-No Derivatives 4.0 license available at http://www.taylorfrancis.com/books/e/9780429465642

1 “The most valuable part of medicine”

The six non-naturals in the long eighteenth century

James Kennaway and Rina Knoeff

DOI: 10.4324/9780429465642

Introduction

As part of his course on the “Institutes of Medicine,” the famous Dutch ­medical teacher Herman Boerhaave (1668–1738) included lectures on the “Diet of Longevity,” which he was in the habit of enlivening with patient case histories. On one occasion students recall Boerhaave reporting that,

There now lives a Man in this City of Leyden, who has seen the Beginning and End of the seventeenth or last Century, being always very healthy; if he is asked by what means he has attained to so great an Age, he usually answers, by a Method you will not imitate, Temperance and Sobriety.

(Boerhaave, 1757, pp. 6.267–277)

This comment about the Leiden centenarian is one of many positive ­eighteenth-century representations of the elderly. In contrast to previous eras, eighteenth-century old folk were no longer just satirically depicted as dying grandfathers heading to their graves, often surrounded by descendants quarrelling about the inheritance (Figure 1.1).

Figure 1.1 Tenth phase in the life cycle with dying centenarian and his heirs fighting over the inheritance, Assuerus van Londerseel, after Nicolaes de Bruyn, 1598–1602.
Courtesy of the Rijksmuseum Amsterdam.

Physicians, particularly in Continental Europe, challenged the seventeenth-century idea that the weakening of old age (i.e. marasmus senilis) was an illness, and they argued that most old people do not die from old age but from a particular disease (Thane, 2003, 2005; Schäfer, 2015). As a result, stories, drawings and paintings often emphasised the possibility of continuing soundness of body as well as mind (Figure 1.2).

Figure 1.2 Engraving of centenarian Willem Opperdoes, born in Haarlem in 1674. Drawn after life by C.V. Noorde, 1774.
Courtesy of the Rijksmuseum Amsterdam.

Moreover, eighteenth-century statistics suggest that in places such as the Netherlands, leaving aside child mortality, most people died past the age of 50 (see Figure 1.3). When asked, the very old themselves generally pointed to a balanced lifestyle (early to bed, moderation in eating and drinking and hard work) as the secret of healthy ageing. With his case report, Boerhaave likewise linked longevity to temperance and sobriety – characteristics that he apparently did not necessarily associate with his students.

Figure 1.3 Death rates of the city of Amsterdam over the year 1778. Published in the Amsterdamsche Courant, 16 January 1779.

Advice on how to live a long life – the field of regimen or dietetics – was a very significant branch of medicine in the long eighteenth century, even if the historiography for the period in general has, for understandable reasons, focused more on important changes in theoretical conceptions of the body and disease. Historians have written extensively about topics such as the mad-doctoring trade or the physiology of the nerves, but regimen has been comparatively neglected. However, in terms of the published works of the period, regimen looms very large indeed, whether in medical literature, such as in the medical textbook by Boerhaave mentioned above, or in the genre of medical advice literature for the public at large. Books such as Scottish physician William Buchan’s bestseller Domestic Medicine, first published in 1769, often included a good deal of discussion of dietetics, along with advice on treating ailments at home. Buchan was expressing a widely held view when he suggested that “Regimen … is the most valuable part of medicine” (1772, p. v).

In order to understand Enlightenment thinking on healthy living, Lifestyle and Medicine in the Enlightenment focuses on the so-called six non-naturals (sex res non naturales), the areas defined by Hippocratic writers as the basis of health management and disease. The terminology of so-called six non-naturals, derived indirectly from the medicine of Antiquity, remained at the heart of discussion of regimen in the long eighteenth century. These were the factors (airs and places; food and drink; exercise; excretion and retention; sleep; and emotions) that usually provided the framework for understanding how lifestyle affected health. They are mentioned as such in Diderot and d’Alembert’s Encyclopédie (1751–1772), even if the entry’s author takes a slightly snooty line on the term as “inappropriate” (1751–1772, p. 11.217).¹ Drawing on Boerhaave, as well as the Scottish physician Archibald Pitcairne and the Montpellier doctor François Boissier de Sauvage, it describes them as those things “which do not compose our nature or our being, but of which the animal economy experiences great effects, great changes, great alterations” (Diderot and d’Alembert, 1751–1772, pp. 11.217–218).²

It is striking that the fundamental rules advocated by medical writers on regimen were essentially sound, with precepts around moderation and exercise that would seem very familiar today. While therapeutics and physiology have changed out of all recognition, in some ways regimen offers an image of remarkable continuity not just since the eighteenth century but since Hippocrates. That also means that dietetic advice was presumably one of the most reliable aspects of eighteenth-century medicine, since its principles of temperance would often have been beneficial in their impact. However, if thinking on how to stay healthy and live a long life reflected a high level of continuity to traditional humoral medicine, newer ideas of mechanical medicine, nervous stimulation and conceptions of individual liberty also played a key role in Enlightenment views of the topic.

The long eighteenth century was in many ways the last age of the six non-naturals. As a comprehensive health programme, they disappeared from clinical medicine in the nineteenth century, as the specific terminology of the non-naturals came to seem scholastic and old-fashioned. More broadly, although medical advice on healthy living never went away, compared to the heroic advances associated with the shift to Parisian hospital medicine and local pathology and developments in disciplines such as bacteriology, dietetics became a real backwater. For much of the period since the mid-nineteenth century, hopes for improvements in longevity and healthy living were primarily fixed on scientific breakthroughs, but in the past few decades there has been what one might see as a pendulum swing back towards the dietetic focus of the eighteenth century. The major health challenges in the prosperous world, and more and more in other countries too, relate to lifestyle issues like obesity, exercise and smoking for which the clinical medicine focused on localised pathology that was so triumphant in the nineteenth and twentieth centuries has few answers. Likewise, in a neoliberal society that increasingly emphasises people’s own responsibility for their own health, the ideas at the root of the six non-naturals are staging a remarkable comeback.

The six non-naturals

The definition and description of the non-naturals have been ascribed to Hippocrates, but they were first formulated by Galen in his commentary on the Hippocratic writings on epidemics and elaborated in his other works on medicine and health. Galen wrote in his Ars medica that,

The causes of change in the body are divided into the ‘necessary’ and the ‘not-necessary’. By ‘necessary’ I mean those which it is impossible for a body not to encounter; by ‘not-necessary’, all others. Constant contact with the ambient air is necessary, as are eating and drinking, waking and sleeping; contact with swords and wild beasts is not. The art concerned with the body is thus performed by means of the former, not of the latter. And if we make a classification of all the necessary factors which alter the body, to each of these will correspond a specific type of healthy cause. One category is contact with the ambient air; another is motion and rest of the body as a whole or of its individual parts. The third is sleep and waking; the fourth, substances taken, the fifth substances voided or retained; the sixth what happens to the soul.

(Singer, 1997, p. 374)

Galen actually never used the term “non-naturals,” but he named them categories of health. The correct application of these categories would lead to the preservation of health, and misuse render them morbid. Everything depended on finding the right balance for each individual constitution. That was the task, Galen pointedly said, for the physician who has a “proper understanding” of the nature of these categories for the formulation of individual regimen, i.e. rules for a healthy lifestyle which depend on a combination of variable factors such as sex, age, labour, social activities and climate.

Galen’s ideas were developed into the format of the six non-naturals in medieval Arabic and Western medicine, and they remained the basis for medical thinking on dietetics well into the early modern period. Curiously, the formulation of new medical ideas based on mechanics and chemistry during the late seventeenth and eighteenth centuries did not lead to a diminishing importance of the non-naturals, as one would perhaps have been inclined to expect. On the contrary, the Hippocratic emphasis on investigating the endless variety of nature was combined with a renewed stress on observation as the physician’s only guide made the non-naturals more important than ever. For instance, Herman Boerhaave’s pupil Jerome Gaub (also known as Hieronymus Gaubius) (1705–1780), famous across Europe for his Institutiones pathologiae medicinalis (1758), stated that it was of paramount importance for the physician to employ mechanics, physics, chemistry and medicine in order to investigate the non-naturals and understand the effects they produce (1778, p. 134).

In order to illuminate the history of dietetics in the long eighteenth century, this book is divided into six parts, each with two chapters devoted to one of the six non-naturals.

1. 1. Airs, waters and places
   The first non-natural is concerned with the effects of the environment on health and disease. It builds on the Hippocratic treatise Airs, Waters, Places, written around 400 bc, and is concerned with the quality of air, the health effects of the winds, the changing of the seasons, the quality of (drinking) water and the richness of the soil upon which people live. Interestingly, it is also about ways of life and social and cultural habits and includes descriptions of national stereotypes.
2. 2. Food and drink
   During the Enlightenment, as worries about luxury lifestyles increased, healthy food and drink were a central concern in medical advice literature. Discussions not only focused on moderation and the question of what constitutes a moderate way of life but also included a constantly shifting debate about healthy and unhealthy food related to the variable factors of sex, age, employment, intelligence and lifestyle.
3. 3. Exercise and rest
   Ever since the origin of the Greek gymnasium, doctors have given advice on the right amount of exercise for the body. In Antiquity, this advice focused on moderation: not too much, not too little, or, in the words of Galen, exercising with a small ball rather than running the marathon (Singer, 1997, pp. 299–304). The eighteenth century saw a revival of classical thinking on exercise, sports and health. These ideas were highly moral and embedded in philosophies of mind–body relations as well as rooted in burgeoning ideas about masculinity and the strength of the nation-state.
4. 4. Sleep and wakefulness
   Although it is a relatively neglected area of research in premodern medicine, sleep and wakefulness were considered important indicators for health and well-being. Based on the Aristotelian treatise De somno et vigilia, physicians speculated about healthy sleep, dreaming, sleep terrors, insomnia, nocturnal emissions and sleepwalking. During the eighteenth century, sleep was closely related to discussions on social behaviour and morality, especially in the context of what Elizabeth Hunter in her chapter calls “the husbandry of time.”
5. 5. Excretion and retention (of faeces, urine, sweat, blood, semen, etc.)
   Since the biological working of the body is involved, the labelling of excretion and retent...

Table of contents

• Cover
• Half-Title
• Series
• Title
• Copyright
• Contents
• List of illustrations
• List of contributors
• Acknowledgements
• 1 “The most valuable part of medicine”: The six non-naturals in the long eighteenth century
• PART 1 Airs, waters and places
• PART 2 Food and drink
• PART 3 Exercise and rest
• PART 4 Sleep and wakefulness
• PART 5 Excretion and retention
• PART 6 Passions and emotions
• EPILOGUE
• Index