This is where the curriculum becomes highly speculative in public texts. Generally, Level 3 is associated with "washing the marrow" and cleansing the brain/nervous system. The energy is driven upward to clear blockages in the head and refine the spirit. This is a dangerous stage if the foundation is not stable.
: This level refines the "Eight Paths" of energy, moving light through the spinal column and limbs to transmute (essence) into (vital energy). Level 4: Mental Mastery and Stillness
The practitioner begins to move this fused energy through the Microcosmic Orbit (Du and Ren meridians) and deeply into the bone marrow and internal organs. The Mechanics
The system is built on the accumulation of (positive energy) and its eventual fusion with Yin Qi (negative energy). Is the Mo Pai Training Manual Real or Fake? - The Dao Bums
of actual meditative state or up to a full year of daily training to "fill" the Dantian. Key Shift: