I wonder if what I see from the trees is the light of a firefly flying about the valley or isaribi (a fire lit on a boat to lure fish) of a fisherman going out to the sea to catch fish (Gyokuyo shu 400, or Hikohimesiki/Kagakusho).
木の間より見ゆるは谷の蛍かもいさりに海人の海へ行くかも（玉葉集400。また孫姫式）