in Thoreau’s Journal:  

At this season of the year, when each leaf acquires its peculiar color, Nature prints this history distinctly, as it were an illuminated edition. Every oak and hickory and birch and aspen sprinkled amid the pines tells its tale a mile off, and you have not to go laboriously through the wood examining the bark and leaves. These facts would be best illustrated by colors, ––green, yellow, red, etc.