The Professor took the old practices and studied them, worked out their mechanical principles and then devised a graded scientific set of tricks, but is based on the elementary laws of mechanics, a study of the equilibrium of the human body, the ways in which it is disturbed, how to recover your own and take advantage of the shifting of the center of gravity of the other person. The first thing that is taught is how to fall down without being hurt, that alone is worth the price of admission and ought to be taught in all our gyms.