The poem was an anthem to Emerson's belief that to 'know thyself' meant knowing the God which Emerson felt existed within each person.
We distinguish the announcements of the soul, its manifestations of its own nature, by the term Revelation. These are always attended by the emotion of the sublime. For this communication is an influx of the Divine mind into our mind. It is an ebb of the individual rivulet before the flowing surges of the sea of life.
We are not separate from the universe. We are part of this one great whole. Mike Rugnetta discusses this from various philosophical and spiritual perspectives on his PBS Idea Channel video below.