According to Osho, expansion in pranayama is followed by return in pratyahara because life thrives as a rhythmic dance of opposites: breath goes out and comes in, creation unfolds and dissolves. Out-breath expands you toward the infinite (fullness); in-breath draws you back to inner emptiness (void). When this polarity stabilizes in awareness, you flow between the two banks—birth and death—and taste the Godlike nature that embraces both.
Life works like breathing: you open out, then come back in, and holding both sides keeps you truly alive and balanced.