I wondered earlier if Emerson's reliance on visual metaphors was idiosyncratic, or if he got it from his intellectual sources. From his journals:
"Musical Eyes. I think sometimes that my lack of Musical ear, is made good to me through my eyes. That which others hear, I see. All the soothing plaintive brisk or romantic moods which corresponding melodies waken in them, I find in the carpet of the wood, in the margin of the pond, in the shade of the hemlock grove, or in the infinite variety & rapid dance of the treetops as I hurry along."
Signet Classics Selected Writings of RWE, p. 83