What was the main purpose of Claude Bernard’s book An Introduction to the Study of Experimental Medicine?

The main purpose of Claude Bernard’s book, An Introduction to the Study of Experimental Medicine (1865), was to demonstrate that for medicine to progress, it must be firmly founded on experimental physiology.1

In this work, Bernard argued that biology and medicine depend on recognizing that life processes are mechanistically determined by physico-chemical forces, rather than by a vague notion of a "vital force". He further established that while physical and chemical sciences provide the necessary foundation for physiology, the field is not entirely reducible to them. Additionally, the book served to advocate for the necessity of vivisection in physiological research and emphasized the importance of using a guiding hypothesis in scientific experimentation.1

Originally intended as a long preface to a larger, uncompleted project, the book remains a seminal text that introduced the concept of the milieu intérieur, or the "internal environment," which is fundamental to our modern understanding of homeostasis.21