The pelvis, in my experience of teaching, is one of the hardest (and most essential, for the somatic therapist) areas to visualize in three dimensions. In the second of Grundy's mechanical 'explanations,' here we see him 'creating' a pelvis from wood or cardboard, in a brave attempt to configure the palpable reality of the pelvis on a flat page. From the standard image of the pelvis as a crosspiece supporting the single pole of the spine on the two pillars of the legs (1), he then shows the primary displacements between the upper and lower poles, showing how the pelvis both curves around (2) and leans back (2a), and then combining these two (3). From here he refines the heart-shaped hole that forms the pelvic floor and the specialities of the pubic bone and other attachment sites (4-7). Take a piece of children's modeling clay, and you can easily follow Grundy's mechanical logic, and learn with your hands the underlying simplicity behind the complexity of the pelvic shape.