Everyone should understand…

At least some of the rudimentary underlying principals governing the mechanism of the human body in motion, rest and sleep.
For example
the leverage possibilities of the bones composing its skeletal framework.
The range and limitation of proper muscle tension and relaxation.
The laws of equilibrium and gravity.
And last but not least how to INHALE and EXHALE; i.e., how to breath properly normally.
Your Health, by Joseph Pilates 1934