in Thoreau’s Journal:

A mild thawy day. The needles of the pine are the touch-stone for the air-any change in that element is revealed to the practiced eye by their livelier green or increased motion.

They are the tell-tales Now they are (the white pine) a cadaverous misty blue-anon a lively silvery light plays on them—& they seem to erect themselves unusually-while the pitch pines are a brighter yellowish green than usual- The sun loves to nestle in the boughs of the pine & pass rays through them.