text establishes the historic struggle of medicine to understand health and disease, highlighting the transition from empirical practices to more systematic, experimental methodologies. It discusses the evolution of medical practice, the value of physiological knowledge, and the critical role of rigorous experimental investigation in establishing accurate medical knowledge. Bernard delineates the distinction between observation and experiment, arguing that while observation reveals natural phenomena, experimentation actively engages with those phenomena to uncover deeper truths about the workings of the body in health and disease. Through this introduction, he sets the stage for a methodologically sound approach to medical research that intertwines theory and practical application. (This is an automatically generated summary.)