Definition - What does Expansion mean?
Expansion is a concept in yoga that describes both physical and spiritual growth. During the physical practice of yoga, the lungs expand through the breath, allowing vital life-force energy to flow through the body. In turn, yoga poses help the yogi grow physically, mentally and spiritually.
It is on the spiritual level, though, that expansion is most significant. On this level, it means letting go of unconscious contraction, thereby allowing the yogi to be present and aware.
Yogapedia explains Expansion
Expansion occurs during yoga practice when the yogi becomes conscious of the breath, physical sensations and energy. As the yogi feels the energy grow, they expand beyond their physical self. The mental training in yoga allows for a state of concentration in which the yogi is able to filter out internal and external clutter. He or she is then able to expand into a state of consciousness that allows the spiritual expansion of yoga to begin.
The goal of yoga is union with the universe, which is achieved as the individual self expands to become one with the higher Self. Rather than being just a small part of a large universe, the Self expands to encompass all that is. Expansion occurs all along the eight-fold path of yoga (as described in the Sutras), culminating with enlightenment that represents union with the Absolute.