Fig. 401.01 Four Vectors of Restraint Define Minimum
System:
Investigation of the requirements for a minimum system.
 One vector of restraint allows ball to define complete
sphere^{__} a threedimensional system.
 Two vectors: a plane^{__} a twodimensional system.
 Three vectors: a line^{__} a onedimensional system.
 Four vectors: a point^{__} no displacement.
 Note the possibility of turbining with the position
otherwise fixed by the four vectors of restraint.
 The four vectors define the tetrahedron: the first
identifiable "system" ^{__} a primary or minimum
subdivision of Universe. The ball lies at the center
of gravity within the tetrahedron.
