Where the self stops and the universe begins

Who can be certain where the self stops and the universe begins?

When we breathe, it is the air from the passing wind that fills our lungs. To our nostrils drifts the fragrance of the woodland flower. When we taste, it is of the earth's flavors and its saltiness. When we eat, it is of the field's corn and its wheat. When we open our eyes they are filled with sunlight and starlight.

Who can be certain where the self stops and the universe begins?