This whole world of illusion could only be produced by duality. In reality there are not two, but one. In order to produce this world, the one Being had to turn Himself into two, and the two had to be different. We have two eyes but one sight, two ears but one hearing, two nostrils but one breath. According to whether the breath flows through the one or the other nostril, it has distinct qualities and faculties; but it is the same breath.