This was the essay Nature, which was published in 1836. By its conception of external Nature as an incarnation of the Divine Mind it struck the fundamental principle of Emerson's religious belief. The essay had a very small circulation at first, though later it became widely known.
LitCharts assigns a color and icon to each theme in Self-Reliance, which you can use to track the themes throughout the work. Emerson and other transcendentalists believed that nature —rather than society, institutions, or the Church—is the ultimate source of truth about the self, God, and existence. As Emerson put it in another essay he.