A Sure Guide in Sickness and Health, authored by William Smith, M.D. in 1776, serves as a comprehensive manual intertwining the principles of natural philosophy and early medical science. The book delves into the fundamental elements of nature, the workings of the human body, and the causes of diseases, emphasizing the importance of understanding the body’s natural processes and the environment’s influence on health. Smith underscores the significance of moderation in diet, the benefits of fresh air, regular exercise, and adequate sleep, advocating for a balanced lifestyle as a cornerstone of health maintenance.​

The guide provides detailed discussions on various ailments, including nervous disorders like epilepsy and palsy, as well as common conditions such as colds and fevers. Smith offers insights into the symptoms and potential treatments of these diseases, reflecting the medical knowledge and practices of the 18th century. His approach combines empirical observations with the prevailing theories of his time, aiming to educate readers on recognizing and managing health issues effectively.​

In addressing chronic conditions like gout, rheumatism, and asthma, Smith emphasizes the role of diet and lifestyle in both the prevention and management of these ailments. He discusses the impact of various foods and the importance of avoiding excesses that could exacerbate health problems. The guide also touches upon the significance of mental well-being, suggesting that emotional health is intrinsically linked to physical health.​

Smith’s work stands as a testament to the early efforts in public health education, aiming to empower individuals with knowledge to make informed decisions about their health. By blending traditional wisdom with the scientific understanding of his era, A Sure Guide in Sickness and Health offers a holistic perspective on health care, emphasizing the importance of harmony between the body, mind, and environment.