Perhaps we have walked over these hills and know them to be carpeted with grass; the greens also of the maples, oaks, cypress, each with its separate hue, attracted our attention. But to-day, from a distance, all these greens are lost in a vaporous hue of blue. It is this effect of atmosphere on color that we will now talk about. It is easy to notice in the case of the hills because of the great quantity of atmosphere that intervenes between us and them. But, if there were a row of maples extending from the hills to us, so placed that we could look along their entire length, we should find the appearance of their color gradually changing, as they recede from our eyes. In a word, to the sensitive eye of the artist the colors of even nearby objects are affected by atmosphere.