From Galens De Sanitate Tuenda to Holistic Health: A Historical Study of the Six Non-Natural Factors

Abstract:

In the second century CE, the theory of the Six Non-Natural Factors (Sex res non naturales) was formulated in the treatise De Sanitate Tuenda (On the Preservation of Health). These factors—air, food and drink, sleep and wakefulness, motion and rest, excretion and retention, and the passions of the mind—represent a comprehensive model of preventive medicine in antiquity. The theory argued that health depends not solely on the body’s innate constitution (res naturales), but also on these modifiable external and behavioral conditions. This article examines the intellectual origins, medical functions, and philosophical implications of the theory, tracing its transmission through Byzantine, Islamic, and Renaissance medicine and comparing it with modern notions of holistic health and lifestyle medicine. Through a historical-philosophical analysis of classical texts and contemporary scholarship, this study reveals that the system was not merely physiological but deeply ethical and ecological. It envisioned health as a dynamic equilibrium between body, mind, and environment—a model that anticipated modern integrative medicine and public health theory. By reconstructing the conceptual continuity between ancient and modern paradigms, this paper argues that the Six Non-Natural Factors form a crucial link in the long intellectual trajectory from humoral balance to systems-based holistic health.