Paraphrase the following Emerson quote: "To a Man laboring under calamity, the heat of his own fire hath sadness in it. Then, there is a kind of contempt of the landscape felt by him who has just lost by death a dear friend."
Emerson prefaces the quote with "Nature always wears the color of the spirit." This helps to accentuate the understanding of the quote. Emerson makes the argument that individuals are bound by their own subjective in the way in which they interact with the external. Nature is thus a reflection of our own sensibilities. It is a reflection of us, and our attitudes towards it mirror our own temperaments.
A paraphrase of Emerson's quote might be that human beings always view nature through the lens of their own experiences. If heat is associated with toil, one's reaction to the natural world is tempered by such a narrative. In the same way, there is a pain experienced in the world that serves as backdrop to the loss of a dear one. The natural world is a reflection of our own experiences and sense of identity. For Emerson, the "unity of both" subjective experience and external reality becomes critical in one's consciousness. In order for this unification to happen, one has to grasp the acceptance of how the external is reflective of our own subjective experiences.