in Thoreau’s Journal:
A fine spring morning. The ground is almost completely bare again. There has been a frost in the night. Now at half past eight it is melted and wets my feet like a dew. The water on the meadow this still bright morning is smooth as in April. I am surprised to hear the strain of a song-sparrow from the river side, thinking of the bluebird, I that instant hear one’s note from deep in the softened air. It is already 40°. By noon it is between 50° and 60°. As the day advances I hear more bluebirds, and see their azure flakes settling on the fence posts. Their short rich warble curls through the air. Its grain now lies parallel to the bluebird’s warble, like boards of the same lot.
It seems to be one of those early springs of which we have heard, but which we have never experienced.