The rhythmic nature of life was recognized in the Bible; Ecclesiastes 3:1, and particularly in one memorable stanza which became the basis for an extremely popular folksong of the 1960s.  I can think of no better words with which to begin this inquiry.

The man who is generally credited with founding that body of theory and practice we now call biorhythms was Wilhelm Fliess.  Fliess was a prominent German doctor who practiced, primarily in Berlin, during the final decades of the nineteenth century and the early decades of the twentieth.  Around the turn of the century, Germany and Austria were regarded as the intellectual homelands of advanced medical theories.

Support for the idea of the cyclical or rhythmic nature of behavior also came from the United States in 1929.  Dr Rex B. Hersey and his associate, Dr. Michael J. Bennett reported a surprising observation after studying a group of workers in a railroad shop.

The theory of biorhythm is based on the premise that there are three powerful cycles or rhythms operating within each and every one of us.  These rhythms begin at the time of our birth.  The clock is, so to speak, set at that moment, and it runs regularly and inexorably until the moment of death.

The three cycles all begin at the same time, but because they are of different lengths begin to stand in a different relationship to one another in just a few hours after birth.

The PHYSICAL rhythm has a duration of 23 days.  It is the rhythm of strength and endurance;  when it is high there is a general feeling of physical well-being, and when it is low there is a feeling of physical fatigue.  On the days when the physical cycle is at its height we not only are stronger, but we feel physically more confident.