When feelings are calm and balanced, the many are experienced as the one. An agitated mind can never have a single vision. It runs along contrary lines. So, it experiences the world, nature and the Cosmos as separate from Brahman. Such vision creates division.
Calm vision reveals unity.
As the vision, so the impression, the view of the world. The head of the family is one person only. But he is viewed by each member of the family from a different point of view.