The concept of "chemical machine" is currently very much in use in studies of the physiology of living bodies especially at the level of their intimate structure. Its appearance, however, has a long history that begins as early as the sixteenth century, when it became apparent that the living body was the abode of complex and fundamental chemical processes. When this awareness met the equally widespread idea that living bodies could be described as "machinery", the problem emerged of reconciling the two approaches, which gave origin to the concept of "chemical machine."