Two basic science specialties that matured in the nineteenth century were instrumental in the transformation of medicine into a scientific discipline and in the process of establishing the evidentiary basis of the fundamental role of the kidney in maintaining homeostasis, whose continued exploration would lead to the emergence of nephrology in the following century. The first specialty was that of chemistry, which progressed from a descriptive to an analytical, organic, biological, and physical science that progressively eroded the animism of the “vital” forces of old and replaced it with the physicochemical forces and laws of chemical reactions that govern the “matters of life”. The second specialty was that of cell biology, which established the cell as the structural and functional unit of living organisms, be they plant or animal. Refined microscopic technologies then helped to identify the structural components of the cell, amongst which the plasma membrane emerged as the most important in regulating the separation of the intracellular machinery from its external environment and thereby maintaining the internal milieu of cells. The interaction of these two specialties (chemistry, cell biology) clarified the functions of the cell in health and disease and extended it to the study of epithelial cell transport. This transforming turn of events established the role of the renal tubules in the vital function of the kidney of maintaining body homeostasis, a function well beyond that of the passive excretory filter of wastes and excess fluids it had been considered theretofore.