Nutrition is a vital process that is carried on only in living organisms. It is a process of development growth, repair, and invigoration. In a complex organism various processes are in continuous operation and these processes contribute to and are intended for the one great end and aim of life—nutrition. It is for this reason alone that we eat and digest, that we breathe, that we secrete and excrete. For this reason alone, the heart and arteries, the veins and lymphatics, perform their varied functions. Function is the great end and aim of life and we are men, strong, vigorous and healthy or feeble, debilitated and worn out, just in the extent to which we have good nutrition.
– Dr. Herbert M. Shelton