Why did Claude Bernard consider a stable internal environment important for living cells?

Claude Bernard, a pioneering French physiologist, emphasized the importance of a stable internal environment—or milieu intérieur—because he believed that all vital mechanisms serve a singular purpose: to preserve the constant conditions necessary for life.1234

By maintaining this chemical balance in and around the cells, an organism can survive despite fluctuations in its external surroundings. Bernard’s concept shifted the understanding of biological processes away from vitalism, establishing that life is maintained through the self-regulation of vital processes, a principle now known as homeostasis. His work demonstrated that the stability of this internal environment is essential for the survival and proper functioning of living cells.231