Edible substances evoke the secretion of thick, concentrated saliva. Why? The answer, obviously, is that this enables the mass of food to pass smoothly through the tube leading from the mouth into the stomach.
Ivan PavlovDo not become archivists of facts. Try to penetrate to the secret of their occurrence, persistently search for the laws which govern them.
Ivan PavlovBut man has still another powerful resource: natural science with its strictly objective methods.
Ivan Pavlov